[wifi] LibreTiny: Eliminate heap allocations in WiFi scan path

esphome/__main__.py

@@ -1,6 +1,5 @@
 # PYTHON_ARGCOMPLETE_OK
 import argparse
-from collections.abc import Callable
 from datetime import datetime
 import functools
 import getpass
@@ -937,21 +936,11 @@ def command_dashboard(args: ArgsProtocol) -> int | None:
     return dashboard.start_dashboard(args)
 
 
-def run_multiple_configs(
-    files: list, command_builder: Callable[[str], list[str]]
-) -> int:
-    """Run a command for each configuration file in a subprocess.
-
-    Args:
-        files: List of configuration files to process.
-        command_builder: Callable that takes a file path and returns a command list.
-
-    Returns:
-        Number of failed files.
-    """
+def command_update_all(args: ArgsProtocol) -> int | None:
     import click
 
     success = {}
+    files = list_yaml_files(args.configuration)
     twidth = 60
 
     def print_bar(middle_text):
@@ -961,19 +950,17 @@ def run_multiple_configs(
         safe_print(f"{half_line}{middle_text}{half_line}")
 
     for f in files:
-        f_path = Path(f) if not isinstance(f, Path) else f
-
-        if any(f_path.name == x for x in SECRETS_FILES):
-            _LOGGER.warning("Skipping secrets file %s", f_path)
-            continue
-
-        safe_print(f"Processing {color(AnsiFore.CYAN, str(f))}")
+        safe_print(f"Updating {color(AnsiFore.CYAN, str(f))}")
         safe_print("-" * twidth)
         safe_print()
-
-        cmd = command_builder(f)
-        rc = run_external_process(*cmd)
-
+        if CORE.dashboard:
+            rc = run_external_process(
+                "esphome", "--dashboard", "run", f, "--no-logs", "--device", "OTA"
+            )
+        else:
+            rc = run_external_process(
+                "esphome", "run", f, "--no-logs", "--device", "OTA"
+            )
         if rc == 0:
             print_bar(f"[{color(AnsiFore.BOLD_GREEN, 'SUCCESS')}] {str(f)}")
             success[f] = True
@@ -988,8 +975,6 @@ def run_multiple_configs(
     print_bar(f"[{color(AnsiFore.BOLD_WHITE, 'SUMMARY')}]")
     failed = 0
     for f in files:
-        if f not in success:
-            continue  # Skipped file
         if success[f]:
             safe_print(f"  - {str(f)}: {color(AnsiFore.GREEN, 'SUCCESS')}")
         else:
@@ -998,17 +983,6 @@ def run_multiple_configs(
     return failed
 
 
-def command_update_all(args: ArgsProtocol) -> int | None:
-    files = list_yaml_files(args.configuration)
-
-    def build_command(f):
-        if CORE.dashboard:
-            return ["esphome", "--dashboard", "run", f, "--no-logs", "--device", "OTA"]
-        return ["esphome", "run", f, "--no-logs", "--device", "OTA"]
-
-    return run_multiple_configs(files, build_command)
-
-
 def command_idedata(args: ArgsProtocol, config: ConfigType) -> int:
     import json
 
@@ -1559,48 +1533,38 @@ def run_esphome(argv):
 
     _LOGGER.info("ESPHome %s", const.__version__)
 
-    # Multiple configurations: use subprocesses to avoid state leakage
-    # between compilations (e.g., LVGL touchscreen state in module globals)
-    if len(args.configuration) > 1:
-        # Build command by reusing argv, replacing all configs with single file
-        # argv[0] is the program path, skip it since we prefix with "esphome"
-        def build_command(f):
-            return (
-                ["esphome"]
-                + [arg for arg in argv[1:] if arg not in args.configuration]
-                + [str(f)]
-            )
+    for conf_path in args.configuration:
+        conf_path = Path(conf_path)
+        if any(conf_path.name == x for x in SECRETS_FILES):
+            _LOGGER.warning("Skipping secrets file %s", conf_path)
+            continue
 
-        return run_multiple_configs(args.configuration, build_command)
+        CORE.config_path = conf_path
+        CORE.dashboard = args.dashboard
 
-    # Single configuration
-    conf_path = Path(args.configuration[0])
-    if any(conf_path.name == x for x in SECRETS_FILES):
-        _LOGGER.warning("Skipping secrets file %s", conf_path)
-        return 0
+        # For logs command, skip updating external components
+        skip_external = args.command == "logs"
+        config = read_config(
+            dict(args.substitution) if args.substitution else {},
+            skip_external_update=skip_external,
+        )
+        if config is None:
+            return 2
+        CORE.config = config
 
-    CORE.config_path = conf_path
-    CORE.dashboard = args.dashboard
+        if args.command not in POST_CONFIG_ACTIONS:
+            safe_print(f"Unknown command {args.command}")
 
-    # For logs command, skip updating external components
-    skip_external = args.command == "logs"
-    config = read_config(
-        dict(args.substitution) if args.substitution else {},
-        skip_external_update=skip_external,
-    )
-    if config is None:
-        return 2
-    CORE.config = config
+        try:
+            rc = POST_CONFIG_ACTIONS[args.command](args, config)
+        except EsphomeError as e:
+            _LOGGER.error(e, exc_info=args.verbose)
+            return 1
+        if rc != 0:
+            return rc
 
-    if args.command not in POST_CONFIG_ACTIONS:
-        safe_print(f"Unknown command {args.command}")
-        return 1
-
-    try:
-        return POST_CONFIG_ACTIONS[args.command](args, config)
-    except EsphomeError as e:
-        _LOGGER.error(e, exc_info=args.verbose)
-        return 1
+        CORE.reset()
+    return 0
 
 
 def main():

esphome/codegen.py

@@ -69,7 +69,6 @@ from esphome.cpp_types import (  # noqa: F401
     JsonObjectConst,
     Parented,
     PollingComponent,
-    StringRef,
     arduino_json_ns,
     bool_,
     const_char_ptr,

esphome/components/am43/am43_base.cpp

@@ -1,12 +1,21 @@
 #include "am43_base.h"
-#include "esphome/core/helpers.h"
 #include <cstring>
+#include <cstdio>
 
 namespace esphome {
 namespace am43 {
 
 const uint8_t START_PACKET[5] = {0x00, 0xff, 0x00, 0x00, 0x9a};
 
+std::string pkt_to_hex(const uint8_t *data, uint16_t len) {
+  char buf[64];
+  memset(buf, 0, 64);
+  for (int i = 0; i < len; i++)
+    sprintf(&buf[i * 2], "%02x", data[i]);
+  std::string ret = buf;
+  return ret;
+}
+
 Am43Packet *Am43Encoder::get_battery_level_request() {
   uint8_t data = 0x1;
   return this->encode_(0xA2, &data, 1);
@@ -64,9 +73,7 @@ Am43Packet *Am43Encoder::encode_(uint8_t command, uint8_t *data, uint8_t length)
   memcpy(&this->packet_.data[7], data, length);
   this->packet_.length = length + 7;
   this->checksum_();
-  char hex_buf[format_hex_size(sizeof(this->packet_.data))];
-  ESP_LOGV("am43", "ENC(%d): 0x%s", this->packet_.length,
-           format_hex_to(hex_buf, this->packet_.data, this->packet_.length));
+  ESP_LOGV("am43", "ENC(%d): 0x%s", packet_.length, pkt_to_hex(packet_.data, packet_.length).c_str());
   return &this->packet_;
 }
 
@@ -81,8 +88,7 @@ void Am43Decoder::decode(const uint8_t *data, uint16_t length) {
   this->has_set_state_response_ = false;
   this->has_position_ = false;
   this->has_pin_response_ = false;
-  char hex_buf[format_hex_size(24)];  // Max expected packet size
-  ESP_LOGV("am43", "DEC(%d): 0x%s", length, format_hex_to(hex_buf, data, length));
+  ESP_LOGV("am43", "DEC(%d): 0x%s", length, pkt_to_hex(data, length).c_str());
 
   if (length < 2 || data[0] != 0x9a)
     return;

esphome/components/anova/anova_base.cpp

@@ -18,31 +18,31 @@ AnovaPacket *AnovaCodec::clean_packet_() {
 
 AnovaPacket *AnovaCodec::get_read_device_status_request() {
   this->current_query_ = READ_DEVICE_STATUS;
-  snprintf((char *) this->packet_.data, sizeof(this->packet_.data), "%s", CMD_READ_DEVICE_STATUS);
+  sprintf((char *) this->packet_.data, "%s", CMD_READ_DEVICE_STATUS);
   return this->clean_packet_();
 }
 
 AnovaPacket *AnovaCodec::get_read_target_temp_request() {
   this->current_query_ = READ_TARGET_TEMPERATURE;
-  snprintf((char *) this->packet_.data, sizeof(this->packet_.data), "%s", CMD_READ_TARGET_TEMP);
+  sprintf((char *) this->packet_.data, "%s", CMD_READ_TARGET_TEMP);
   return this->clean_packet_();
 }
 
 AnovaPacket *AnovaCodec::get_read_current_temp_request() {
   this->current_query_ = READ_CURRENT_TEMPERATURE;
-  snprintf((char *) this->packet_.data, sizeof(this->packet_.data), "%s", CMD_READ_CURRENT_TEMP);
+  sprintf((char *) this->packet_.data, "%s", CMD_READ_CURRENT_TEMP);
   return this->clean_packet_();
 }
 
 AnovaPacket *AnovaCodec::get_read_unit_request() {
   this->current_query_ = READ_UNIT;
-  snprintf((char *) this->packet_.data, sizeof(this->packet_.data), "%s", CMD_READ_UNIT);
+  sprintf((char *) this->packet_.data, "%s", CMD_READ_UNIT);
   return this->clean_packet_();
 }
 
 AnovaPacket *AnovaCodec::get_read_data_request() {
   this->current_query_ = READ_DATA;
-  snprintf((char *) this->packet_.data, sizeof(this->packet_.data), "%s", CMD_READ_DATA);
+  sprintf((char *) this->packet_.data, "%s", CMD_READ_DATA);
   return this->clean_packet_();
 }
 
@@ -50,25 +50,25 @@ AnovaPacket *AnovaCodec::get_set_target_temp_request(float temperature) {
   this->current_query_ = SET_TARGET_TEMPERATURE;
   if (this->fahrenheit_)
     temperature = ctof(temperature);
-  snprintf((char *) this->packet_.data, sizeof(this->packet_.data), CMD_SET_TARGET_TEMP, temperature);
+  sprintf((char *) this->packet_.data, CMD_SET_TARGET_TEMP, temperature);
   return this->clean_packet_();
 }
 
 AnovaPacket *AnovaCodec::get_set_unit_request(char unit) {
   this->current_query_ = SET_UNIT;
-  snprintf((char *) this->packet_.data, sizeof(this->packet_.data), CMD_SET_TEMP_UNIT, unit);
+  sprintf((char *) this->packet_.data, CMD_SET_TEMP_UNIT, unit);
   return this->clean_packet_();
 }
 
 AnovaPacket *AnovaCodec::get_start_request() {
   this->current_query_ = START;
-  snprintf((char *) this->packet_.data, sizeof(this->packet_.data), "%s", CMD_START);
+  sprintf((char *) this->packet_.data, CMD_START);
   return this->clean_packet_();
 }
 
 AnovaPacket *AnovaCodec::get_stop_request() {
   this->current_query_ = STOP;
-  snprintf((char *) this->packet_.data, sizeof(this->packet_.data), "%s", CMD_STOP);
+  sprintf((char *) this->packet_.data, CMD_STOP);
   return this->clean_packet_();
 }
 

esphome/components/api/api_connection.cpp

@@ -1712,16 +1712,17 @@ void APIConnection::on_home_assistant_state_response(const HomeAssistantStateRes
     }
 
     // Create null-terminated state for callback (parse_number needs null-termination)
-    // HA state max length is 255 characters, but attributes can be much longer
-    // Use stack buffer for common case (states), heap fallback for large attributes
-    size_t state_len = msg.state.size();
-    SmallBufferWithHeapFallback<MAX_STATE_LEN + 1> state_buf_alloc(state_len + 1);
-    char *state_buf = reinterpret_cast<char *>(state_buf_alloc.get());
-    if (state_len > 0) {
-      memcpy(state_buf, msg.state.c_str(), state_len);
+    // HA state max length is 255, so 256 byte buffer covers all cases
+    char state_buf[256];
+    size_t copy_len = msg.state.size();
+    if (copy_len >= sizeof(state_buf)) {
+      copy_len = sizeof(state_buf) - 1;  // Truncate to leave space for null terminator
     }
-    state_buf[state_len] = '\0';
-    it.callback(StringRef(state_buf, state_len));
+    if (copy_len > 0) {
+      memcpy(state_buf, msg.state.c_str(), copy_len);
+    }
+    state_buf[copy_len] = '\0';
+    it.callback(StringRef(state_buf, copy_len));
   }
 }
 #endif

esphome/components/ccs811/ccs811.cpp

@@ -81,8 +81,8 @@ void CCS811Component::setup() {
            bootloader_version, application_version);
   if (this->version_ != nullptr) {
     char version[20];  // "15.15.15 (0xffff)" is 17 chars, plus NUL, plus wiggle room
-    buf_append_printf(version, sizeof(version), 0, "%d.%d.%d (0x%02x)", (application_version >> 12 & 15),
-                      (application_version >> 8 & 15), (application_version >> 4 & 15), application_version);
+    sprintf(version, "%d.%d.%d (0x%02x)", (application_version >> 12 & 15), (application_version >> 8 & 15),
+            (application_version >> 4 & 15), application_version);
     ESP_LOGD(TAG, "publishing version state: %s", version);
     this->version_->publish_state(version);
   }

esphome/components/ch422g/ch422g.cpp

@@ -133,7 +133,7 @@ bool CH422GGPIOPin::digital_read() { return this->parent_->digital_read(this->pi
 
 void CH422GGPIOPin::digital_write(bool value) { this->parent_->digital_write(this->pin_, value ^ this->inverted_); }
 size_t CH422GGPIOPin::dump_summary(char *buffer, size_t len) const {
-  return buf_append_printf(buffer, len, 0, "EXIO%u via CH422G", this->pin_);
+  return snprintf(buffer, len, "EXIO%u via CH422G", this->pin_);
 }
 void CH422GGPIOPin::set_flags(gpio::Flags flags) {
   flags_ = flags;

esphome/components/cse7766/cse7766.cpp

@@ -207,24 +207,20 @@ void CSE7766Component::parse_data_() {
 
 #if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERY_VERBOSE
   {
-    // Buffer: 7 + 15 + 33 + 15 + 25 = 95 chars max + null, rounded to 128 for safety margin.
-    // Float sizes with %.4f can be up to 11 chars for large values (e.g., 999999.9999).
-    char buf[128];
-    size_t pos = buf_append_printf(buf, sizeof(buf), 0, "Parsed:");
+    std::string buf = "Parsed:";
     if (have_voltage) {
-      pos = buf_append_printf(buf, sizeof(buf), pos, " V=%.4fV", voltage);
+      buf += str_sprintf(" V=%fV", voltage);
     }
     if (have_current) {
-      pos = buf_append_printf(buf, sizeof(buf), pos, " I=%.4fmA (~%.4fmA)", current * 1000.0f,
-                              calculated_current * 1000.0f);
+      buf += str_sprintf(" I=%fmA (~%fmA)", current * 1000.0f, calculated_current * 1000.0f);
     }
     if (have_power) {
-      pos = buf_append_printf(buf, sizeof(buf), pos, " P=%.4fW", power);
+      buf += str_sprintf(" P=%fW", power);
     }
     if (energy != 0.0f) {
-      buf_append_printf(buf, sizeof(buf), pos, " E=%.4fkWh (%u)", energy, cf_pulses);
+      buf += str_sprintf(" E=%fkWh (%u)", energy, cf_pulses);
     }
-    ESP_LOGVV(TAG, "%s", buf);
+    ESP_LOGVV(TAG, "%s", buf.c_str());
   }
 #endif
 }

esphome/components/daikin_arc/daikin_arc.cpp

@@ -258,9 +258,8 @@ bool DaikinArcClimate::parse_state_frame_(const uint8_t frame[]) {
   }
 
   char buf[DAIKIN_STATE_FRAME_SIZE * 3 + 1] = {0};
-  size_t pos = 0;
   for (size_t i = 0; i < DAIKIN_STATE_FRAME_SIZE; i++) {
-    pos = buf_append_printf(buf, sizeof(buf), pos, "%02x ", frame[i]);
+    sprintf(buf, "%s%02x ", buf, frame[i]);
   }
   ESP_LOGD(TAG, "FRAME %s", buf);
 
@@ -350,9 +349,8 @@ bool DaikinArcClimate::on_receive(remote_base::RemoteReceiveData data) {
   if (data.expect_item(DAIKIN_HEADER_MARK, DAIKIN_HEADER_SPACE)) {
     valid_daikin_frame = true;
     size_t bytes_count = data.size() / 2 / 8;
-    size_t buf_size = bytes_count * 3 + 1;
-    std::unique_ptr<char[]> buf(new char[buf_size]());  // value-initialize (zero-fill)
-    size_t buf_pos = 0;
+    std::unique_ptr<char[]> buf(new char[bytes_count * 3 + 1]);
+    buf[0] = '\0';
     for (size_t i = 0; i < bytes_count; i++) {
       uint8_t byte = 0;
       for (int8_t bit = 0; bit < 8; bit++) {
@@ -363,19 +361,19 @@ bool DaikinArcClimate::on_receive(remote_base::RemoteReceiveData data) {
           break;
         }
       }
-      buf_pos = buf_append_printf(buf.get(), buf_size, buf_pos, "%02x ", byte);
+      sprintf(buf.get(), "%s%02x ", buf.get(), byte);
     }
     ESP_LOGD(TAG, "WHOLE FRAME %s  size: %d", buf.get(), data.size());
   }
   if (!valid_daikin_frame) {
-    char sbuf[16 * 10 + 1] = {0};
-    size_t sbuf_pos = 0;
+    char sbuf[16 * 10 + 1];
+    sbuf[0] = '\0';
     for (size_t j = 0; j < static_cast<size_t>(data.size()); j++) {
       if ((j - 2) % 16 == 0) {
         if (j > 0) {
           ESP_LOGD(TAG, "DATA %04x: %s", (j - 16 > 0xffff ? 0 : j - 16), sbuf);
         }
-        sbuf_pos = 0;
+        sbuf[0] = '\0';
       }
       char type_ch = ' ';
       // debug_tolerance = 25%
@@ -403,10 +401,9 @@ bool DaikinArcClimate::on_receive(remote_base::RemoteReceiveData data) {
         type_ch = '0';
 
       if (abs(data[j]) > 100000) {
-        sbuf_pos = buf_append_printf(sbuf, sizeof(sbuf), sbuf_pos, "%-5d[%c] ", data[j] > 0 ? 99999 : -99999, type_ch);
+        sprintf(sbuf, "%s%-5d[%c] ", sbuf, data[j] > 0 ? 99999 : -99999, type_ch);
       } else {
-        sbuf_pos =
-            buf_append_printf(sbuf, sizeof(sbuf), sbuf_pos, "%-5d[%c] ", (int) (round(data[j] / 10.) * 10), type_ch);
+        sprintf(sbuf, "%s%-5d[%c] ", sbuf, (int) (round(data[j] / 10.) * 10), type_ch);
       }
       if (j + 1 == static_cast<size_t>(data.size())) {
         ESP_LOGD(TAG, "DATA %04x: %s", (j - 8 > 0xffff ? 0 : j - 8), sbuf);

esphome/components/debug/debug_component.cpp

@@ -30,7 +30,7 @@ void DebugComponent::dump_config() {
 
   char device_info_buffer[DEVICE_INFO_BUFFER_SIZE];
   ESP_LOGD(TAG, "ESPHome version %s", ESPHOME_VERSION);
-  size_t pos = buf_append_printf(device_info_buffer, DEVICE_INFO_BUFFER_SIZE, 0, "%s", ESPHOME_VERSION);
+  size_t pos = buf_append(device_info_buffer, DEVICE_INFO_BUFFER_SIZE, 0, "%s", ESPHOME_VERSION);
 
   this->free_heap_ = get_free_heap_();
   ESP_LOGD(TAG, "Free Heap Size: %" PRIu32 " bytes", this->free_heap_);

esphome/components/debug/debug_component.h

@@ -5,6 +5,12 @@
 #include "esphome/core/helpers.h"
 #include "esphome/core/macros.h"
 #include <span>
+#include <cstdarg>
+#include <cstdio>
+#include <algorithm>
+#ifdef USE_ESP8266
+#include <pgmspace.h>
+#endif
 
 #ifdef USE_SENSOR
 #include "esphome/components/sensor/sensor.h"
@@ -19,7 +25,40 @@ namespace debug {
 static constexpr size_t DEVICE_INFO_BUFFER_SIZE = 256;
 static constexpr size_t RESET_REASON_BUFFER_SIZE = 128;
 
-// buf_append_printf is now provided by esphome/core/helpers.h
+#ifdef USE_ESP8266
+// ESP8266: Use vsnprintf_P to keep format strings in flash (PROGMEM)
+// Format strings must be wrapped with PSTR() macro
+inline size_t buf_append_p(char *buf, size_t size, size_t pos, PGM_P fmt, ...) {
+  if (pos >= size) {
+    return size;
+  }
+  va_list args;
+  va_start(args, fmt);
+  int written = vsnprintf_P(buf + pos, size - pos, fmt, args);
+  va_end(args);
+  if (written < 0) {
+    return pos;  // encoding error
+  }
+  return std::min(pos + static_cast<size_t>(written), size);
+}
+#define buf_append(buf, size, pos, fmt, ...) buf_append_p(buf, size, pos, PSTR(fmt), ##__VA_ARGS__)
+#else
+/// Safely append formatted string to buffer, returning new position (capped at size)
+__attribute__((format(printf, 4, 5))) inline size_t buf_append(char *buf, size_t size, size_t pos, const char *fmt,
+                                                               ...) {
+  if (pos >= size) {
+    return size;
+  }
+  va_list args;
+  va_start(args, fmt);
+  int written = vsnprintf(buf + pos, size - pos, fmt, args);
+  va_end(args);
+  if (written < 0) {
+    return pos;  // encoding error
+  }
+  return std::min(pos + static_cast<size_t>(written), size);
+}
+#endif
 
 class DebugComponent : public PollingComponent {
  public:

esphome/components/debug/debug_esp32.cpp

@@ -173,8 +173,8 @@ size_t DebugComponent::get_device_info_(std::span<char, DEVICE_INFO_BUFFER_SIZE>
   uint32_t flash_size = ESP.getFlashChipSize() / 1024;       // NOLINT
   uint32_t flash_speed = ESP.getFlashChipSpeed() / 1000000;  // NOLINT
   ESP_LOGD(TAG, "Flash Chip: Size=%" PRIu32 "kB Speed=%" PRIu32 "MHz Mode=%s", flash_size, flash_speed, flash_mode);
-  pos = buf_append_printf(buf, size, pos, "|Flash: %" PRIu32 "kB Speed:%" PRIu32 "MHz Mode:%s", flash_size, flash_speed,
-                          flash_mode);
+  pos = buf_append(buf, size, pos, "|Flash: %" PRIu32 "kB Speed:%" PRIu32 "MHz Mode:%s", flash_size, flash_speed,
+                   flash_mode);
 #endif
 
   esp_chip_info_t info;
@@ -182,52 +182,52 @@ size_t DebugComponent::get_device_info_(std::span<char, DEVICE_INFO_BUFFER_SIZE>
   const char *model = ESPHOME_VARIANT;
 
   // Build features string
-  pos = buf_append_printf(buf, size, pos, "|Chip: %s Features:", model);
+  pos = buf_append(buf, size, pos, "|Chip: %s Features:", model);
   bool first_feature = true;
   for (const auto &feature : CHIP_FEATURES) {
     if (info.features & feature.bit) {
-      pos = buf_append_printf(buf, size, pos, "%s%s", first_feature ? "" : ", ", feature.name);
+      pos = buf_append(buf, size, pos, "%s%s", first_feature ? "" : ", ", feature.name);
       first_feature = false;
       info.features &= ~feature.bit;
     }
   }
   if (info.features != 0) {
-    pos = buf_append_printf(buf, size, pos, "%sOther:0x%" PRIx32, first_feature ? "" : ", ", info.features);
+    pos = buf_append(buf, size, pos, "%sOther:0x%" PRIx32, first_feature ? "" : ", ", info.features);
   }
   ESP_LOGD(TAG, "Chip: Model=%s, Cores=%u, Revision=%u", model, info.cores, info.revision);
-  pos = buf_append_printf(buf, size, pos, " Cores:%u Revision:%u", info.cores, info.revision);
+  pos = buf_append(buf, size, pos, " Cores:%u Revision:%u", info.cores, info.revision);
 
   uint32_t cpu_freq_mhz = arch_get_cpu_freq_hz() / 1000000;
   ESP_LOGD(TAG, "CPU Frequency: %" PRIu32 " MHz", cpu_freq_mhz);
-  pos = buf_append_printf(buf, size, pos, "|CPU Frequency: %" PRIu32 " MHz", cpu_freq_mhz);
+  pos = buf_append(buf, size, pos, "|CPU Frequency: %" PRIu32 " MHz", cpu_freq_mhz);
 
   // Framework detection
 #ifdef USE_ARDUINO
   ESP_LOGD(TAG, "Framework: Arduino");
-  pos = buf_append_printf(buf, size, pos, "|Framework: Arduino");
+  pos = buf_append(buf, size, pos, "|Framework: Arduino");
 #elif defined(USE_ESP32)
   ESP_LOGD(TAG, "Framework: ESP-IDF");
-  pos = buf_append_printf(buf, size, pos, "|Framework: ESP-IDF");
+  pos = buf_append(buf, size, pos, "|Framework: ESP-IDF");
 #else
   ESP_LOGW(TAG, "Framework: UNKNOWN");
-  pos = buf_append_printf(buf, size, pos, "|Framework: UNKNOWN");
+  pos = buf_append(buf, size, pos, "|Framework: UNKNOWN");
 #endif
 
   ESP_LOGD(TAG, "ESP-IDF Version: %s", esp_get_idf_version());
-  pos = buf_append_printf(buf, size, pos, "|ESP-IDF: %s", esp_get_idf_version());
+  pos = buf_append(buf, size, pos, "|ESP-IDF: %s", esp_get_idf_version());
 
   uint8_t mac[6];
   get_mac_address_raw(mac);
   ESP_LOGD(TAG, "EFuse MAC: %02X:%02X:%02X:%02X:%02X:%02X", mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
-  pos = buf_append_printf(buf, size, pos, "|EFuse MAC: %02X:%02X:%02X:%02X:%02X:%02X", mac[0], mac[1], mac[2], mac[3],
-                          mac[4], mac[5]);
+  pos = buf_append(buf, size, pos, "|EFuse MAC: %02X:%02X:%02X:%02X:%02X:%02X", mac[0], mac[1], mac[2], mac[3], mac[4],
+                   mac[5]);
 
   char reason_buffer[RESET_REASON_BUFFER_SIZE];
   const char *reset_reason = get_reset_reason_(std::span<char, RESET_REASON_BUFFER_SIZE>(reason_buffer));
-  pos = buf_append_printf(buf, size, pos, "|Reset: %s", reset_reason);
+  pos = buf_append(buf, size, pos, "|Reset: %s", reset_reason);
 
   const char *wakeup_cause = get_wakeup_cause_(std::span<char, RESET_REASON_BUFFER_SIZE>(reason_buffer));
-  pos = buf_append_printf(buf, size, pos, "|Wakeup: %s", wakeup_cause);
+  pos = buf_append(buf, size, pos, "|Wakeup: %s", wakeup_cause);
 
   return pos;
 }

esphome/components/debug/debug_esp8266.cpp

@@ -3,80 +3,21 @@
 #include "esphome/core/log.h"
 #include <Esp.h>
 
-extern "C" {
-#include <user_interface.h>
-
-// Global reset info struct populated by SDK at boot
-extern struct rst_info resetInfo;
-
-// Core version - either a string pointer or a version number to format as hex
-extern uint32_t core_version;
-extern const char *core_release;
-}
-
 namespace esphome {
 namespace debug {
 
 static const char *const TAG = "debug";
 
-// Get reset reason string from reason code (no heap allocation)
-// Returns LogString* pointing to flash (PROGMEM) on ESP8266
-static const LogString *get_reset_reason_str(uint32_t reason) {
-  switch (reason) {
-    case REASON_DEFAULT_RST:
-      return LOG_STR("Power On");
-    case REASON_WDT_RST:
-      return LOG_STR("Hardware Watchdog");
-    case REASON_EXCEPTION_RST:
-      return LOG_STR("Exception");
-    case REASON_SOFT_WDT_RST:
-      return LOG_STR("Software Watchdog");
-    case REASON_SOFT_RESTART:
-      return LOG_STR("Software/System restart");
-    case REASON_DEEP_SLEEP_AWAKE:
-      return LOG_STR("Deep-Sleep Wake");
-    case REASON_EXT_SYS_RST:
-      return LOG_STR("External System");
-    default:
-      return LOG_STR("Unknown");
-  }
-}
-
-// Size for core version hex buffer
-static constexpr size_t CORE_VERSION_BUFFER_SIZE = 12;
-
-// Get core version string (no heap allocation)
-// Returns either core_release directly or formats core_version as hex into provided buffer
-static const char *get_core_version_str(std::span<char, CORE_VERSION_BUFFER_SIZE> buffer) {
-  if (core_release != nullptr) {
-    return core_release;
-  }
-  snprintf_P(buffer.data(), CORE_VERSION_BUFFER_SIZE, PSTR("%08x"), core_version);
-  return buffer.data();
-}
-
-// Size for reset info buffer
-static constexpr size_t RESET_INFO_BUFFER_SIZE = 200;
-
-// Get detailed reset info string (no heap allocation)
-// For watchdog/exception resets, includes detailed exception info
-static const char *get_reset_info_str(std::span<char, RESET_INFO_BUFFER_SIZE> buffer, uint32_t reason) {
-  if (reason >= REASON_WDT_RST && reason <= REASON_SOFT_WDT_RST) {
-    snprintf_P(buffer.data(), RESET_INFO_BUFFER_SIZE,
-               PSTR("Fatal exception:%d flag:%d (%s) epc1:0x%08x epc2:0x%08x epc3:0x%08x excvaddr:0x%08x depc:0x%08x"),
-               static_cast<int>(resetInfo.exccause), static_cast<int>(reason),
-               LOG_STR_ARG(get_reset_reason_str(reason)), resetInfo.epc1, resetInfo.epc2, resetInfo.epc3,
-               resetInfo.excvaddr, resetInfo.depc);
-    return buffer.data();
-  }
-  return LOG_STR_ARG(get_reset_reason_str(reason));
-}
-
 const char *DebugComponent::get_reset_reason_(std::span<char, RESET_REASON_BUFFER_SIZE> buffer) {
-  // Copy from flash to provided buffer
-  strncpy_P(buffer.data(), (PGM_P) get_reset_reason_str(resetInfo.reason), RESET_REASON_BUFFER_SIZE - 1);
-  buffer[RESET_REASON_BUFFER_SIZE - 1] = '\0';
-  return buffer.data();
+  char *buf = buffer.data();
+#if !defined(CLANG_TIDY)
+  String reason = ESP.getResetReason();  // NOLINT
+  snprintf_P(buf, RESET_REASON_BUFFER_SIZE, PSTR("%s"), reason.c_str());
+  return buf;
+#else
+  buf[0] = '\0';
+  return buf;
+#endif
 }
 
 const char *DebugComponent::get_wakeup_cause_(std::span<char, RESET_REASON_BUFFER_SIZE> buffer) {
@@ -92,42 +33,37 @@ size_t DebugComponent::get_device_info_(std::span<char, DEVICE_INFO_BUFFER_SIZE>
   constexpr size_t size = DEVICE_INFO_BUFFER_SIZE;
   char *buf = buffer.data();
 
-  const LogString *flash_mode;
+  const char *flash_mode;
   switch (ESP.getFlashChipMode()) {  // NOLINT(readability-static-accessed-through-instance)
     case FM_QIO:
-      flash_mode = LOG_STR("QIO");
+      flash_mode = "QIO";
       break;
     case FM_QOUT:
-      flash_mode = LOG_STR("QOUT");
+      flash_mode = "QOUT";
       break;
     case FM_DIO:
-      flash_mode = LOG_STR("DIO");
+      flash_mode = "DIO";
       break;
     case FM_DOUT:
-      flash_mode = LOG_STR("DOUT");
+      flash_mode = "DOUT";
       break;
     default:
-      flash_mode = LOG_STR("UNKNOWN");
+      flash_mode = "UNKNOWN";
   }
-  uint32_t flash_size = ESP.getFlashChipSize() / 1024;       // NOLINT(readability-static-accessed-through-instance)
-  uint32_t flash_speed = ESP.getFlashChipSpeed() / 1000000;  // NOLINT(readability-static-accessed-through-instance)
-  ESP_LOGD(TAG, "Flash Chip: Size=%" PRIu32 "kB Speed=%" PRIu32 "MHz Mode=%s", flash_size, flash_speed,
-           LOG_STR_ARG(flash_mode));
-  pos = buf_append_printf(buf, size, pos, "|Flash: %" PRIu32 "kB Speed:%" PRIu32 "MHz Mode:%s", flash_size, flash_speed,
-                          LOG_STR_ARG(flash_mode));
+  uint32_t flash_size = ESP.getFlashChipSize() / 1024;       // NOLINT
+  uint32_t flash_speed = ESP.getFlashChipSpeed() / 1000000;  // NOLINT
+  ESP_LOGD(TAG, "Flash Chip: Size=%" PRIu32 "kB Speed=%" PRIu32 "MHz Mode=%s", flash_size, flash_speed, flash_mode);
+  pos = buf_append(buf, size, pos, "|Flash: %" PRIu32 "kB Speed:%" PRIu32 "MHz Mode:%s", flash_size, flash_speed,
+                   flash_mode);
 
+#if !defined(CLANG_TIDY)
   char reason_buffer[RESET_REASON_BUFFER_SIZE];
-  const char *reset_reason = get_reset_reason_(reason_buffer);
-  char core_version_buffer[CORE_VERSION_BUFFER_SIZE];
-  char reset_info_buffer[RESET_INFO_BUFFER_SIZE];
-  // NOLINTBEGIN(readability-static-accessed-through-instance)
+  const char *reset_reason = get_reset_reason_(std::span<char, RESET_REASON_BUFFER_SIZE>(reason_buffer));
   uint32_t chip_id = ESP.getChipId();
   uint8_t boot_version = ESP.getBootVersion();
   uint8_t boot_mode = ESP.getBootMode();
   uint8_t cpu_freq = ESP.getCpuFreqMHz();
   uint32_t flash_chip_id = ESP.getFlashChipId();
-  const char *sdk_version = ESP.getSdkVersion();
-  // NOLINTEND(readability-static-accessed-through-instance)
 
   ESP_LOGD(TAG,
            "Chip ID: 0x%08" PRIX32 "\n"
@@ -138,18 +74,19 @@ size_t DebugComponent::get_device_info_(std::span<char, DEVICE_INFO_BUFFER_SIZE>
            "Flash Chip ID=0x%08" PRIX32 "\n"
            "Reset Reason: %s\n"
            "Reset Info: %s",
-           chip_id, sdk_version, get_core_version_str(core_version_buffer), boot_version, boot_mode, cpu_freq,
-           flash_chip_id, reset_reason, get_reset_info_str(reset_info_buffer, resetInfo.reason));
+           chip_id, ESP.getSdkVersion(), ESP.getCoreVersion().c_str(), boot_version, boot_mode, cpu_freq, flash_chip_id,
+           reset_reason, ESP.getResetInfo().c_str());
 
-  pos = buf_append_printf(buf, size, pos, "|Chip: 0x%08" PRIX32, chip_id);
-  pos = buf_append_printf(buf, size, pos, "|SDK: %s", sdk_version);
-  pos = buf_append_printf(buf, size, pos, "|Core: %s", get_core_version_str(core_version_buffer));
-  pos = buf_append_printf(buf, size, pos, "|Boot: %u", boot_version);
-  pos = buf_append_printf(buf, size, pos, "|Mode: %u", boot_mode);
-  pos = buf_append_printf(buf, size, pos, "|CPU: %u", cpu_freq);
-  pos = buf_append_printf(buf, size, pos, "|Flash: 0x%08" PRIX32, flash_chip_id);
-  pos = buf_append_printf(buf, size, pos, "|Reset: %s", reset_reason);
-  pos = buf_append_printf(buf, size, pos, "|%s", get_reset_info_str(reset_info_buffer, resetInfo.reason));
+  pos = buf_append(buf, size, pos, "|Chip: 0x%08" PRIX32, chip_id);
+  pos = buf_append(buf, size, pos, "|SDK: %s", ESP.getSdkVersion());
+  pos = buf_append(buf, size, pos, "|Core: %s", ESP.getCoreVersion().c_str());
+  pos = buf_append(buf, size, pos, "|Boot: %u", boot_version);
+  pos = buf_append(buf, size, pos, "|Mode: %u", boot_mode);
+  pos = buf_append(buf, size, pos, "|CPU: %u", cpu_freq);
+  pos = buf_append(buf, size, pos, "|Flash: 0x%08" PRIX32, flash_chip_id);
+  pos = buf_append(buf, size, pos, "|Reset: %s", reset_reason);
+  pos = buf_append(buf, size, pos, "|%s", ESP.getResetInfo().c_str());
+#endif
 
   return pos;
 }

esphome/components/debug/debug_libretiny.cpp

@@ -36,12 +36,12 @@ size_t DebugComponent::get_device_info_(std::span<char, DEVICE_INFO_BUFFER_SIZE>
            lt_get_version(), lt_cpu_get_model_name(), lt_cpu_get_model(), lt_cpu_get_freq_mhz(), mac_id,
            lt_get_board_code(), flash_kib, ram_kib, reset_reason);
 
-  pos = buf_append_printf(buf, size, pos, "|Version: %s", LT_BANNER_STR + 10);
-  pos = buf_append_printf(buf, size, pos, "|Reset Reason: %s", reset_reason);
-  pos = buf_append_printf(buf, size, pos, "|Chip Name: %s", lt_cpu_get_model_name());
-  pos = buf_append_printf(buf, size, pos, "|Chip ID: 0x%06" PRIX32, mac_id);
-  pos = buf_append_printf(buf, size, pos, "|Flash: %" PRIu32 " KiB", flash_kib);
-  pos = buf_append_printf(buf, size, pos, "|RAM: %" PRIu32 " KiB", ram_kib);
+  pos = buf_append(buf, size, pos, "|Version: %s", LT_BANNER_STR + 10);
+  pos = buf_append(buf, size, pos, "|Reset Reason: %s", reset_reason);
+  pos = buf_append(buf, size, pos, "|Chip Name: %s", lt_cpu_get_model_name());
+  pos = buf_append(buf, size, pos, "|Chip ID: 0x%06" PRIX32, mac_id);
+  pos = buf_append(buf, size, pos, "|Flash: %" PRIu32 " KiB", flash_kib);
+  pos = buf_append(buf, size, pos, "|RAM: %" PRIu32 " KiB", ram_kib);
 
   return pos;
 }

esphome/components/debug/debug_rp2040.cpp

@@ -19,7 +19,7 @@ size_t DebugComponent::get_device_info_(std::span<char, DEVICE_INFO_BUFFER_SIZE>
 
   uint32_t cpu_freq = rp2040.f_cpu();
   ESP_LOGD(TAG, "CPU Frequency: %" PRIu32, cpu_freq);
-  pos = buf_append_printf(buf, size, pos, "|CPU Frequency: %" PRIu32, cpu_freq);
+  pos = buf_append(buf, size, pos, "|CPU Frequency: %" PRIu32, cpu_freq);
 
   return pos;
 }

esphome/components/debug/debug_zephyr.cpp

@@ -20,9 +20,9 @@ static size_t append_reset_reason(char *buf, size_t size, size_t pos, bool set,
     return pos;
   }
   if (pos > 0) {
-    pos = buf_append_printf(buf, size, pos, ", ");
+    pos = buf_append(buf, size, pos, ", ");
   }
-  return buf_append_printf(buf, size, pos, "%s", reason);
+  return buf_append(buf, size, pos, "%s", reason);
 }
 
 static inline uint32_t read_mem_u32(uintptr_t addr) {
@@ -140,7 +140,7 @@ size_t DebugComponent::get_device_info_(std::span<char, DEVICE_INFO_BUFFER_SIZE>
   const char *supply_status =
       (nrf_power_mainregstatus_get(NRF_POWER) == NRF_POWER_MAINREGSTATUS_NORMAL) ? "Normal voltage." : "High voltage.";
   ESP_LOGD(TAG, "Main supply status: %s", supply_status);
-  pos = buf_append_printf(buf, size, pos, "|Main supply status: %s", supply_status);
+  pos = buf_append(buf, size, pos, "|Main supply status: %s", supply_status);
 
   // Regulator stage 0
   if (nrf_power_mainregstatus_get(NRF_POWER) == NRF_POWER_MAINREGSTATUS_HIGH) {
@@ -172,16 +172,16 @@ size_t DebugComponent::get_device_info_(std::span<char, DEVICE_INFO_BUFFER_SIZE>
         reg0_voltage = "???V";
     }
     ESP_LOGD(TAG, "Regulator stage 0: %s, %s", reg0_type, reg0_voltage);
-    pos = buf_append_printf(buf, size, pos, "|Regulator stage 0: %s, %s", reg0_type, reg0_voltage);
+    pos = buf_append(buf, size, pos, "|Regulator stage 0: %s, %s", reg0_type, reg0_voltage);
   } else {
     ESP_LOGD(TAG, "Regulator stage 0: disabled");
-    pos = buf_append_printf(buf, size, pos, "|Regulator stage 0: disabled");
+    pos = buf_append(buf, size, pos, "|Regulator stage 0: disabled");
   }
 
   // Regulator stage 1
   const char *reg1_type = nrf_power_dcdcen_get(NRF_POWER) ? "DC/DC" : "LDO";
   ESP_LOGD(TAG, "Regulator stage 1: %s", reg1_type);
-  pos = buf_append_printf(buf, size, pos, "|Regulator stage 1: %s", reg1_type);
+  pos = buf_append(buf, size, pos, "|Regulator stage 1: %s", reg1_type);
 
   // USB power state
   const char *usb_state;
@@ -195,7 +195,7 @@ size_t DebugComponent::get_device_info_(std::span<char, DEVICE_INFO_BUFFER_SIZE>
     usb_state = "disconnected";
   }
   ESP_LOGD(TAG, "USB power state: %s", usb_state);
-  pos = buf_append_printf(buf, size, pos, "|USB power state: %s", usb_state);
+  pos = buf_append(buf, size, pos, "|USB power state: %s", usb_state);
 
   // Power-fail comparator
   bool enabled;
@@ -300,14 +300,14 @@ size_t DebugComponent::get_device_info_(std::span<char, DEVICE_INFO_BUFFER_SIZE>
           break;
       }
       ESP_LOGD(TAG, "Power-fail comparator: %s, VDDH: %s", pof_voltage, vddh_voltage);
-      pos = buf_append_printf(buf, size, pos, "|Power-fail comparator: %s, VDDH: %s", pof_voltage, vddh_voltage);
+      pos = buf_append(buf, size, pos, "|Power-fail comparator: %s, VDDH: %s", pof_voltage, vddh_voltage);
     } else {
       ESP_LOGD(TAG, "Power-fail comparator: %s", pof_voltage);
-      pos = buf_append_printf(buf, size, pos, "|Power-fail comparator: %s", pof_voltage);
+      pos = buf_append(buf, size, pos, "|Power-fail comparator: %s", pof_voltage);
     }
   } else {
     ESP_LOGD(TAG, "Power-fail comparator: disabled");
-    pos = buf_append_printf(buf, size, pos, "|Power-fail comparator: disabled");
+    pos = buf_append(buf, size, pos, "|Power-fail comparator: disabled");
   }
 
   auto package = [](uint32_t value) {

esphome/components/dfrobot_sen0395/commands.cpp

@@ -127,9 +127,7 @@ DetRangeCfgCommand::DetRangeCfgCommand(float min1, float max1, float min2, float
     this->min2_ = min2 = this->max2_ = max2 = this->min3_ = min3 = this->max3_ = max3 = this->min4_ = min4 =
         this->max4_ = max4 = -1;
 
-    char buf[72];  // max 72: "detRangeCfg -1 "(15) + 8 * (float(5) + space(1)) + null
-    snprintf(buf, sizeof(buf), "detRangeCfg -1 %.0f %.0f", min1 / 0.15, max1 / 0.15);
-    this->cmd_ = buf;
+    this->cmd_ = str_sprintf("detRangeCfg -1 %.0f %.0f", min1 / 0.15, max1 / 0.15);
   } else if (min3 < 0 || max3 < 0) {
     this->min1_ = min1 = round(min1 / 0.15) * 0.15;
     this->max1_ = max1 = round(max1 / 0.15) * 0.15;
@@ -137,10 +135,7 @@ DetRangeCfgCommand::DetRangeCfgCommand(float min1, float max1, float min2, float
     this->max2_ = max2 = round(max2 / 0.15) * 0.15;
     this->min3_ = min3 = this->max3_ = max3 = this->min4_ = min4 = this->max4_ = max4 = -1;
 
-    char buf[72];  // max 72: "detRangeCfg -1 "(15) + 8 * (float(5) + space(1)) + null
-    snprintf(buf, sizeof(buf), "detRangeCfg -1 %.0f %.0f %.0f %.0f", min1 / 0.15, max1 / 0.15, min2 / 0.15,
-             max2 / 0.15);
-    this->cmd_ = buf;
+    this->cmd_ = str_sprintf("detRangeCfg -1 %.0f %.0f %.0f %.0f", min1 / 0.15, max1 / 0.15, min2 / 0.15, max2 / 0.15);
   } else if (min4 < 0 || max4 < 0) {
     this->min1_ = min1 = round(min1 / 0.15) * 0.15;
     this->max1_ = max1 = round(max1 / 0.15) * 0.15;
@@ -150,10 +145,9 @@ DetRangeCfgCommand::DetRangeCfgCommand(float min1, float max1, float min2, float
     this->max3_ = max3 = round(max3 / 0.15) * 0.15;
     this->min4_ = min4 = this->max4_ = max4 = -1;
 
-    char buf[72];  // max 72: "detRangeCfg -1 "(15) + 8 * (float(5) + space(1)) + null
-    snprintf(buf, sizeof(buf), "detRangeCfg -1 %.0f %.0f %.0f %.0f %.0f %.0f", min1 / 0.15, max1 / 0.15, min2 / 0.15,
-             max2 / 0.15, min3 / 0.15, max3 / 0.15);
-    this->cmd_ = buf;
+    this->cmd_ = str_sprintf("detRangeCfg -1 "
+                             "%.0f %.0f %.0f %.0f %.0f %.0f",
+                             min1 / 0.15, max1 / 0.15, min2 / 0.15, max2 / 0.15, min3 / 0.15, max3 / 0.15);
   } else {
     this->min1_ = min1 = round(min1 / 0.15) * 0.15;
     this->max1_ = max1 = round(max1 / 0.15) * 0.15;
@@ -164,10 +158,10 @@ DetRangeCfgCommand::DetRangeCfgCommand(float min1, float max1, float min2, float
     this->min4_ = min4 = round(min4 / 0.15) * 0.15;
     this->max4_ = max4 = round(max4 / 0.15) * 0.15;
 
-    char buf[72];  // max 72: "detRangeCfg -1 "(15) + 8 * (float(5) + space(1)) + null
-    snprintf(buf, sizeof(buf), "detRangeCfg -1 %.0f %.0f %.0f %.0f %.0f %.0f %.0f %.0f", min1 / 0.15, max1 / 0.15,
-             min2 / 0.15, max2 / 0.15, min3 / 0.15, max3 / 0.15, min4 / 0.15, max4 / 0.15);
-    this->cmd_ = buf;
+    this->cmd_ = str_sprintf("detRangeCfg -1 "
+                             "%.0f %.0f %.0f %.0f %.0f %.0f %.0f %.0f",
+                             min1 / 0.15, max1 / 0.15, min2 / 0.15, max2 / 0.15, min3 / 0.15, max3 / 0.15, min4 / 0.15,
+                             max4 / 0.15);
   }
 
   this->min1_ = min1;
@@ -209,10 +203,7 @@ SetLatencyCommand::SetLatencyCommand(float delay_after_detection, float delay_af
   delay_after_disappear = std::round(delay_after_disappear / 0.025f) * 0.025f;
   this->delay_after_detection_ = clamp(delay_after_detection, 0.0f, 1638.375f);
   this->delay_after_disappear_ = clamp(delay_after_disappear, 0.0f, 1638.375f);
-  // max 32: "setLatency "(11) + float(8) + " "(1) + float(8) + null, rounded to 32
-  char buf[32];
-  snprintf(buf, sizeof(buf), "setLatency %.03f %.03f", this->delay_after_detection_, this->delay_after_disappear_);
-  this->cmd_ = buf;
+  this->cmd_ = str_sprintf("setLatency %.03f %.03f", this->delay_after_detection_, this->delay_after_disappear_);
 };
 
 uint8_t SetLatencyCommand::on_message(std::string &message) {

esphome/components/dfrobot_sen0395/commands.h

@@ -75,8 +75,8 @@ class SetLatencyCommand : public Command {
 class SensorCfgStartCommand : public Command {
  public:
   SensorCfgStartCommand(bool startup_mode) : startup_mode_(startup_mode) {
-    char tmp_cmd[20];  // "sensorCfgStart " (15) + "0/1" (1) + null = 17
-    buf_append_printf(tmp_cmd, sizeof(tmp_cmd), 0, "sensorCfgStart %d", startup_mode);
+    char tmp_cmd[20] = {0};
+    sprintf(tmp_cmd, "sensorCfgStart %d", startup_mode);
     cmd_ = std::string(tmp_cmd);
   }
   uint8_t on_message(std::string &message) override;
@@ -142,8 +142,8 @@ class SensitivityCommand : public Command {
   SensitivityCommand(uint8_t sensitivity) : sensitivity_(sensitivity) {
     if (sensitivity > 9)
       sensitivity_ = sensitivity = 9;
-    char tmp_cmd[20];  // "setSensitivity " (15) + "0-9" (1) + null = 17
-    buf_append_printf(tmp_cmd, sizeof(tmp_cmd), 0, "setSensitivity %d", sensitivity);
+    char tmp_cmd[20] = {0};
+    sprintf(tmp_cmd, "setSensitivity %d", sensitivity);
     cmd_ = std::string(tmp_cmd);
   };
   uint8_t on_message(std::string &message) override;

esphome/components/dsmr/__init__.py

@@ -25,13 +25,29 @@ dsmr_ns = cg.esphome_ns.namespace("esphome::dsmr")
 Dsmr = dsmr_ns.class_("Dsmr", cg.Component, uart.UARTDevice)
 
 
+def _validate_key(value):
+    value = cv.string_strict(value)
+    parts = [value[i : i + 2] for i in range(0, len(value), 2)]
+    if len(parts) != 16:
+        raise cv.Invalid("Decryption key must consist of 16 hexadecimal numbers")
+    parts_int = []
+    if any(len(part) != 2 for part in parts):
+        raise cv.Invalid("Decryption key must be format XX")
+    for part in parts:
+        try:
+            parts_int.append(int(part, 16))
+        except ValueError:
+            # pylint: disable=raise-missing-from
+            raise cv.Invalid("Decryption key must be hex values from 00 to FF")
+
+    return "".join(f"{part:02X}" for part in parts_int)
+
+
 CONFIG_SCHEMA = cv.All(
     cv.Schema(
         {
             cv.GenerateID(): cv.declare_id(Dsmr),
-            cv.Optional(CONF_DECRYPTION_KEY): lambda value: cv.bind_key(
-                value, name="Decryption key"
-            ),
+            cv.Optional(CONF_DECRYPTION_KEY): _validate_key,
             cv.Optional(CONF_CRC_CHECK, default=True): cv.boolean,
             cv.Optional(CONF_GAS_MBUS_ID, default=1): cv.int_,
             cv.Optional(CONF_WATER_MBUS_ID, default=2): cv.int_,

esphome/components/dsmr/dsmr.cpp

@@ -1,5 +1,4 @@
 #include "dsmr.h"
-#include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
 
 #include <AES.h>
@@ -295,8 +294,8 @@ void Dsmr::dump_config() {
   DSMR_TEXT_SENSOR_LIST(DSMR_LOG_TEXT_SENSOR, )
 }
 
-void Dsmr::set_decryption_key(const char *decryption_key) {
-  if (decryption_key == nullptr || decryption_key[0] == '\0') {
+void Dsmr::set_decryption_key(const std::string &decryption_key) {
+  if (decryption_key.empty()) {
     ESP_LOGI(TAG, "Disabling decryption");
     this->decryption_key_.clear();
     if (this->crypt_telegram_ != nullptr) {
@@ -306,15 +305,21 @@ void Dsmr::set_decryption_key(const char *decryption_key) {
     return;
   }
 
-  if (!parse_hex(decryption_key, this->decryption_key_, 16)) {
-    ESP_LOGE(TAG, "Error, decryption key must be 32 hex characters");
-    this->decryption_key_.clear();
+  if (decryption_key.length() != 32) {
+    ESP_LOGE(TAG, "Error, decryption key must be 32 character long");
     return;
   }
+  this->decryption_key_.clear();
 
   ESP_LOGI(TAG, "Decryption key is set");
   // Verbose level prints decryption key
-  ESP_LOGV(TAG, "Using decryption key: %s", decryption_key);
+  ESP_LOGV(TAG, "Using decryption key: %s", decryption_key.c_str());
+
+  char temp[3] = {0};
+  for (int i = 0; i < 16; i++) {
+    strncpy(temp, &(decryption_key.c_str()[i * 2]), 2);
+    this->decryption_key_.push_back(std::strtoul(temp, nullptr, 16));
+  }
 
   if (this->crypt_telegram_ == nullptr) {
     this->crypt_telegram_ = new uint8_t[this->max_telegram_len_];  // NOLINT

esphome/components/dsmr/dsmr.h

@@ -63,7 +63,7 @@ class Dsmr : public Component, public uart::UARTDevice {
 
   void dump_config() override;
 
-  void set_decryption_key(const char *decryption_key);
+  void set_decryption_key(const std::string &decryption_key);
   void set_max_telegram_length(size_t length) { this->max_telegram_len_ = length; }
   void set_request_pin(GPIOPin *request_pin) { this->request_pin_ = request_pin; }
   void set_request_interval(uint32_t interval) { this->request_interval_ = interval; }

esphome/components/esp32_ble/ble_uuid.h

@@ -46,8 +46,6 @@ class ESPBTUUID {
 
   esp_bt_uuid_t get_uuid() const;
 
-  // Remove before 2026.8.0
-  ESPDEPRECATED("Use to_str() instead. Removed in 2026.8.0", "2026.2.0")
   std::string to_string() const;
   const char *to_str(std::span<char, UUID_STR_LEN> output) const;
 

esphome/components/esp32_hosted/update/esp32_hosted_update.cpp

@@ -69,10 +69,7 @@ void Esp32HostedUpdate::setup() {
   // Get coprocessor version
   esp_hosted_coprocessor_fwver_t ver_info;
   if (esp_hosted_get_coprocessor_fwversion(&ver_info) == ESP_OK) {
-    // 16 bytes: "255.255.255" (11 chars) + null + safety margin
-    char buf[16];
-    snprintf(buf, sizeof(buf), "%d.%d.%d", ver_info.major1, ver_info.minor1, ver_info.patch1);
-    this->update_info_.current_version = buf;
+    this->update_info_.current_version = str_sprintf("%d.%d.%d", ver_info.major1, ver_info.minor1, ver_info.patch1);
   } else {
     this->update_info_.current_version = "unknown";
   }

esphome/components/esp8266/core.cpp

@@ -6,11 +6,7 @@
 #include "esphome/core/helpers.h"
 #include "preferences.h"
 #include <Arduino.h>
-#include <core_esp8266_features.h>
-
-extern "C" {
-#include <user_interface.h>
-}
+#include <Esp.h>
 
 namespace esphome {
 
@@ -20,19 +16,23 @@ void IRAM_ATTR HOT delay(uint32_t ms) { ::delay(ms); }
 uint32_t IRAM_ATTR HOT micros() { return ::micros(); }
 void IRAM_ATTR HOT delayMicroseconds(uint32_t us) { delay_microseconds_safe(us); }
 void arch_restart() {
-  system_restart();
+  ESP.restart();  // NOLINT(readability-static-accessed-through-instance)
   // restart() doesn't always end execution
   while (true) {  // NOLINT(clang-diagnostic-unreachable-code)
     yield();
   }
 }
 void arch_init() {}
-void IRAM_ATTR HOT arch_feed_wdt() { system_soft_wdt_feed(); }
+void IRAM_ATTR HOT arch_feed_wdt() {
+  ESP.wdtFeed();  // NOLINT(readability-static-accessed-through-instance)
+}
 
 uint8_t progmem_read_byte(const uint8_t *addr) {
   return pgm_read_byte(addr);  // NOLINT
 }
-uint32_t IRAM_ATTR HOT arch_get_cpu_cycle_count() { return esp_get_cycle_count(); }
+uint32_t IRAM_ATTR HOT arch_get_cpu_cycle_count() {
+  return ESP.getCycleCount();  // NOLINT(readability-static-accessed-through-instance)
+}
 uint32_t arch_get_cpu_freq_hz() { return F_CPU; }
 
 void force_link_symbols() {

esphome/components/esp8266/gpio.cpp

@@ -99,7 +99,7 @@ void ESP8266GPIOPin::pin_mode(gpio::Flags flags) {
 }
 
 size_t ESP8266GPIOPin::dump_summary(char *buffer, size_t len) const {
-  return buf_append_printf(buffer, len, 0, "GPIO%u", this->pin_);
+  return snprintf(buffer, len, "GPIO%u", this->pin_);
 }
 
 bool ESP8266GPIOPin::digital_read() {

esphome/components/event/__init__.py

@@ -90,7 +90,9 @@ async def setup_event_core_(var, config, *, event_types: list[str]):
 
     for conf in config.get(CONF_ON_EVENT, []):
         trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], var)
-        await automation.build_automation(trigger, [(cg.StringRef, "event_type")], conf)
+        await automation.build_automation(
+            trigger, [(cg.std_string, "event_type")], conf
+        )
 
     cg.add(var.set_event_types(event_types))
 

esphome/components/event/automation.h

@@ -14,10 +14,10 @@ template<typename... Ts> class TriggerEventAction : public Action<Ts...>, public
   void play(const Ts &...x) override { this->parent_->trigger(this->event_type_.value(x...)); }
 };
 
-class EventTrigger : public Trigger<StringRef> {
+class EventTrigger : public Trigger<std::string> {
  public:
   EventTrigger(Event *event) {
-    event->add_on_event_callback([this](StringRef event_type) { this->trigger(event_type); });
+    event->add_on_event_callback([this](const std::string &event_type) { this->trigger(event_type); });
   }
 };
 

esphome/components/event/event.cpp

@@ -23,7 +23,7 @@ void Event::trigger(const std::string &event_type) {
   }
   this->last_event_type_ = found;
   ESP_LOGD(TAG, "'%s' >> '%s'", this->get_name().c_str(), this->last_event_type_);
-  this->event_callback_.call(StringRef(found));
+  this->event_callback_.call(event_type);
 #if defined(USE_EVENT) && defined(USE_CONTROLLER_REGISTRY)
   ControllerRegistry::notify_event(this);
 #endif
@@ -45,7 +45,7 @@ void Event::set_event_types(const std::vector<const char *> &event_types) {
   this->last_event_type_ = nullptr;  // Reset when types change
 }
 
-void Event::add_on_event_callback(std::function<void(StringRef event_type)> &&callback) {
+void Event::add_on_event_callback(std::function<void(const std::string &event_type)> &&callback) {
   this->event_callback_.add(std::move(callback));
 }
 

esphome/components/event/event.h

@@ -70,10 +70,10 @@ class Event : public EntityBase, public EntityBase_DeviceClass {
   /// Check if an event has been triggered.
   bool has_event() const { return this->last_event_type_ != nullptr; }
 
-  void add_on_event_callback(std::function<void(StringRef event_type)> &&callback);
+  void add_on_event_callback(std::function<void(const std::string &event_type)> &&callback);
 
  protected:
-  LazyCallbackManager<void(StringRef event_type)> event_callback_;
+  LazyCallbackManager<void(const std::string &event_type)> event_callback_;
   FixedVector<const char *> types_;
 
  private:

esphome/components/ezo/ezo.cpp

@@ -160,7 +160,7 @@ void EZOSensor::loop() {
   this->commands_.pop_front();
 }
 
-void EZOSensor::add_command_(const char *command, EzoCommandType command_type, uint16_t delay_ms) {
+void EZOSensor::add_command_(const std::string &command, EzoCommandType command_type, uint16_t delay_ms) {
   std::unique_ptr<EzoCommand> ezo_command(new EzoCommand);
   ezo_command->command = command;
   ezo_command->command_type = command_type;
@@ -169,17 +169,13 @@ void EZOSensor::add_command_(const char *command, EzoCommandType command_type, u
 }
 
 void EZOSensor::set_calibration_point_(EzoCalibrationType type, float value) {
-  // max 21: "Cal,"(4) + type(4) + ","(1) + float(11) + null; use 24 for safety
-  char payload[24];
-  snprintf(payload, sizeof(payload), "Cal,%s,%0.2f", EZO_CALIBRATION_TYPE_STRINGS[type], value);
+  std::string payload = str_sprintf("Cal,%s,%0.2f", EZO_CALIBRATION_TYPE_STRINGS[type], value);
   this->add_command_(payload, EzoCommandType::EZO_CALIBRATION, 900);
 }
 
 void EZOSensor::set_address(uint8_t address) {
   if (address > 0 && address < 128) {
-    // max 8: "I2C,"(4) + uint8(3) + null
-    char payload[8];
-    snprintf(payload, sizeof(payload), "I2C,%u", address);
+    std::string payload = str_sprintf("I2C,%u", address);
     this->new_address_ = address;
     this->add_command_(payload, EzoCommandType::EZO_I2C);
   } else {
@@ -198,9 +194,7 @@ void EZOSensor::get_slope() { this->add_command_("Slope,?", EzoCommandType::EZO_
 void EZOSensor::get_t() { this->add_command_("T,?", EzoCommandType::EZO_T); }
 
 void EZOSensor::set_t(float value) {
-  // max 14 bytes: "T,"(2) + float with "%0.2f" (up to 11 chars) + null(1); use 16 for alignment
-  char payload[16];
-  snprintf(payload, sizeof(payload), "T,%0.2f", value);
+  std::string payload = str_sprintf("T,%0.2f", value);
   this->add_command_(payload, EzoCommandType::EZO_T);
 }
 
@@ -221,9 +215,7 @@ void EZOSensor::set_calibration_point_high(float value) {
 }
 
 void EZOSensor::set_calibration_generic(float value) {
-  // exact 16 bytes: "Cal," (4) + float with "%0.2f" (up to 11 chars, e.g. "-9999999.99") + null (1) = 16
-  char payload[16];
-  snprintf(payload, sizeof(payload), "Cal,%0.2f", value);
+  std::string payload = str_sprintf("Cal,%0.2f", value);
   this->add_command_(payload, EzoCommandType::EZO_CALIBRATION, 900);
 }
 
@@ -231,11 +223,13 @@ void EZOSensor::clear_calibration() { this->add_command_("Cal,clear", EzoCommand
 
 void EZOSensor::get_led_state() { this->add_command_("L,?", EzoCommandType::EZO_LED); }
 
-void EZOSensor::set_led_state(bool on) { this->add_command_(on ? "L,1" : "L,0", EzoCommandType::EZO_LED); }
-
-void EZOSensor::send_custom(const std::string &to_send) {
-  this->add_command_(to_send.c_str(), EzoCommandType::EZO_CUSTOM);
+void EZOSensor::set_led_state(bool on) {
+  std::string to_send = "L,";
+  to_send += on ? "1" : "0";
+  this->add_command_(to_send, EzoCommandType::EZO_LED);
 }
 
+void EZOSensor::send_custom(const std::string &to_send) { this->add_command_(to_send, EzoCommandType::EZO_CUSTOM); }
+
 }  // namespace ezo
 }  // namespace esphome

esphome/components/ezo/ezo.h

@@ -92,7 +92,7 @@ class EZOSensor : public sensor::Sensor, public PollingComponent, public i2c::I2
   std::deque<std::unique_ptr<EzoCommand>> commands_;
   int new_address_;
 
-  void add_command_(const char *command, EzoCommandType command_type, uint16_t delay_ms = 300);
+  void add_command_(const std::string &command, EzoCommandType command_type, uint16_t delay_ms = 300);
 
   void set_calibration_point_(EzoCalibrationType type, float value);
 

esphome/components/ezo_pmp/ezo_pmp.cpp

@@ -318,93 +318,90 @@ void EzoPMP::send_next_command_() {
   switch (this->next_command_) {
     // Read Commands
     case EZO_PMP_COMMAND_READ_DOSING:  // Page 54
-      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "D,?");
+      command_buffer_length = sprintf((char *) command_buffer, "D,?");
       break;
 
     case EZO_PMP_COMMAND_READ_SINGLE_REPORT:  // Single Report (page 53)
-      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "R");
+      command_buffer_length = sprintf((char *) command_buffer, "R");
       break;
 
     case EZO_PMP_COMMAND_READ_MAX_FLOW_RATE:
-      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "DC,?");
+      command_buffer_length = sprintf((char *) command_buffer, "DC,?");
       break;
 
     case EZO_PMP_COMMAND_READ_PAUSE_STATUS:
-      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "P,?");
+      command_buffer_length = sprintf((char *) command_buffer, "P,?");
       break;
 
     case EZO_PMP_COMMAND_READ_TOTAL_VOLUME_DOSED:
-      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "TV,?");
+      command_buffer_length = sprintf((char *) command_buffer, "TV,?");
       break;
 
     case EZO_PMP_COMMAND_READ_ABSOLUTE_TOTAL_VOLUME_DOSED:
-      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "ATV,?");
+      command_buffer_length = sprintf((char *) command_buffer, "ATV,?");
       break;
 
     case EZO_PMP_COMMAND_READ_CALIBRATION_STATUS:
-      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "Cal,?");
+      command_buffer_length = sprintf((char *) command_buffer, "Cal,?");
       break;
 
     case EZO_PMP_COMMAND_READ_PUMP_VOLTAGE:
-      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "PV,?");
+      command_buffer_length = sprintf((char *) command_buffer, "PV,?");
       break;
 
       // Non-Read Commands
 
     case EZO_PMP_COMMAND_FIND:  // Find (page 52)
-      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "Find");
+      command_buffer_length = sprintf((char *) command_buffer, "Find");
       wait_time_for_command = 60000;  // This command will block all updates for a minute
       break;
 
     case EZO_PMP_COMMAND_DOSE_CONTINUOUSLY:  // Continuous Dispensing (page 54)
-      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "D,*");
+      command_buffer_length = sprintf((char *) command_buffer, "D,*");
       break;
 
     case EZO_PMP_COMMAND_CLEAR_TOTAL_VOLUME_DOSED:  // Clear Total Volume Dosed (page 64)
-      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "Clear");
+      command_buffer_length = sprintf((char *) command_buffer, "Clear");
       break;
 
     case EZO_PMP_COMMAND_CLEAR_CALIBRATION:  // Clear Calibration (page 65)
-      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "Cal,clear");
+      command_buffer_length = sprintf((char *) command_buffer, "Cal,clear");
       break;
 
     case EZO_PMP_COMMAND_PAUSE_DOSING:  // Pause (page 61)
-      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "P");
+      command_buffer_length = sprintf((char *) command_buffer, "P");
       break;
 
     case EZO_PMP_COMMAND_STOP_DOSING:  // Stop (page 62)
-      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "X");
+      command_buffer_length = sprintf((char *) command_buffer, "X");
       break;
 
       // Non-Read commands with parameters
 
     case EZO_PMP_COMMAND_DOSE_VOLUME:  // Volume Dispensing (page 55)
-      command_buffer_length =
-          snprintf((char *) command_buffer, sizeof(command_buffer), "D,%0.1f", this->next_command_volume_);
+      command_buffer_length = sprintf((char *) command_buffer, "D,%0.1f", this->next_command_volume_);
       break;
 
     case EZO_PMP_COMMAND_DOSE_VOLUME_OVER_TIME:  // Dose over time (page 56)
-      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "D,%0.1f,%i",
-                                       this->next_command_volume_, this->next_command_duration_);
+      command_buffer_length =
+          sprintf((char *) command_buffer, "D,%0.1f,%i", this->next_command_volume_, this->next_command_duration_);
       break;
 
     case EZO_PMP_COMMAND_DOSE_WITH_CONSTANT_FLOW_RATE:  // Constant Flow Rate (page 57)
-      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "DC,%0.1f,%i",
-                                       this->next_command_volume_, this->next_command_duration_);
+      command_buffer_length =
+          sprintf((char *) command_buffer, "DC,%0.1f,%i", this->next_command_volume_, this->next_command_duration_);
       break;
 
     case EZO_PMP_COMMAND_SET_CALIBRATION_VOLUME:  // Set Calibration Volume (page 65)
-      command_buffer_length =
-          snprintf((char *) command_buffer, sizeof(command_buffer), "Cal,%0.2f", this->next_command_volume_);
+      command_buffer_length = sprintf((char *) command_buffer, "Cal,%0.2f", this->next_command_volume_);
       break;
 
     case EZO_PMP_COMMAND_CHANGE_I2C_ADDRESS:  // Change I2C Address (page 73)
-      command_buffer_length =
-          snprintf((char *) command_buffer, sizeof(command_buffer), "I2C,%i", this->next_command_duration_);
+      command_buffer_length = sprintf((char *) command_buffer, "I2C,%i", this->next_command_duration_);
       break;
 
     case EZO_PMP_COMMAND_EXEC_ARBITRARY_COMMAND_ADDRESS:  // Run an arbitrary command
-      command_buffer_length = snprintf((char *) command_buffer, sizeof(command_buffer), "%s", this->arbitrary_command_);
+      command_buffer_length = sprintf((char *) command_buffer, this->arbitrary_command_, this->next_command_duration_);
       ESP_LOGI(TAG, "Sending arbitrary command: %s", (char *) command_buffer);
       break;
 

esphome/components/fan/__init__.py

@@ -77,7 +77,7 @@ FanSpeedSetTrigger = fan_ns.class_(
     "FanSpeedSetTrigger", automation.Trigger.template(cg.int_)
 )
 FanPresetSetTrigger = fan_ns.class_(
-    "FanPresetSetTrigger", automation.Trigger.template(cg.StringRef)
+    "FanPresetSetTrigger", automation.Trigger.template(cg.std_string)
 )
 
 FanIsOnCondition = fan_ns.class_("FanIsOnCondition", automation.Condition.template())
@@ -287,7 +287,7 @@ async def setup_fan_core_(var, config):
         await automation.build_automation(trigger, [(cg.int_, "x")], conf)
     for conf in config.get(CONF_ON_PRESET_SET, []):
         trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], var)
-        await automation.build_automation(trigger, [(cg.StringRef, "x")], conf)
+        await automation.build_automation(trigger, [(cg.std_string, "x")], conf)
 
 
 async def register_fan(var, config):

esphome/components/fan/automation.h

@@ -208,7 +208,7 @@ class FanSpeedSetTrigger : public Trigger<int> {
   int last_speed_;
 };
 
-class FanPresetSetTrigger : public Trigger<StringRef> {
+class FanPresetSetTrigger : public Trigger<std::string> {
  public:
   FanPresetSetTrigger(Fan *state) {
     state->add_on_state_callback([this, state]() {
@@ -216,7 +216,7 @@ class FanPresetSetTrigger : public Trigger<StringRef> {
       auto should_trigger = preset_mode != this->last_preset_mode_;
       this->last_preset_mode_ = preset_mode;
       if (should_trigger) {
-        this->trigger(preset_mode);
+        this->trigger(std::string(preset_mode));
       }
     });
     this->last_preset_mode_ = state->get_preset_mode();

esphome/components/gdk101/gdk101.cpp

@@ -163,10 +163,9 @@ bool GDK101Component::read_fw_version_(uint8_t *data) {
       return false;
     }
 
-    // max 8: "255.255" (7 chars) + null
-    char buf[8];
-    snprintf(buf, sizeof(buf), "%d.%d", data[0], data[1]);
-    this->fw_version_text_sensor_->publish_state(buf);
+    const std::string fw_version_str = str_sprintf("%d.%d", data[0], data[1]);
+
+    this->fw_version_text_sensor_->publish_state(fw_version_str);
   }
 #endif  // USE_TEXT_SENSOR
   return true;

esphome/components/homeassistant/number/homeassistant_number.cpp

@@ -97,7 +97,7 @@ void HomeassistantNumber::control(float value) {
   entity_value.key = VALUE_KEY;
   // Stack buffer - no heap allocation; %g produces shortest representation
   char value_buf[16];
-  buf_append_printf(value_buf, sizeof(value_buf), 0, "%g", value);
+  snprintf(value_buf, sizeof(value_buf), "%g", value);
   entity_value.value = StringRef(value_buf);
 
   api::global_api_server->send_homeassistant_action(resp);

esphome/components/i2c/i2c.cpp

@@ -42,8 +42,8 @@ ErrorCode I2CDevice::read_register16(uint16_t a_register, uint8_t *data, size_t
 }
 
 ErrorCode I2CDevice::write_register(uint8_t a_register, const uint8_t *data, size_t len) const {
-  SmallBufferWithHeapFallback<17> buffer_alloc(len + 1);  // Most I2C writes are <= 16 bytes
-  uint8_t *buffer = buffer_alloc.get();
+  SmallBufferWithHeapFallback<17> buffer_alloc;  // Most I2C writes are <= 16 bytes
+  uint8_t *buffer = buffer_alloc.get(len + 1);
 
   buffer[0] = a_register;
   std::copy(data, data + len, buffer + 1);
@@ -51,8 +51,8 @@ ErrorCode I2CDevice::write_register(uint8_t a_register, const uint8_t *data, siz
 }
 
 ErrorCode I2CDevice::write_register16(uint16_t a_register, const uint8_t *data, size_t len) const {
-  SmallBufferWithHeapFallback<18> buffer_alloc(len + 2);  // Most I2C writes are <= 16 bytes + 2 for register
-  uint8_t *buffer = buffer_alloc.get();
+  SmallBufferWithHeapFallback<18> buffer_alloc;  // Most I2C writes are <= 16 bytes + 2 for register
+  uint8_t *buffer = buffer_alloc.get(len + 2);
 
   buffer[0] = a_register >> 8;
   buffer[1] = a_register;

esphome/components/i2c/i2c_bus.h

@@ -11,6 +11,22 @@
 namespace esphome {
 namespace i2c {
 
+/// @brief Helper class for efficient buffer allocation - uses stack for small sizes, heap for large
+template<size_t STACK_SIZE> class SmallBufferWithHeapFallback {
+ public:
+  uint8_t *get(size_t size) {
+    if (size <= STACK_SIZE) {
+      return this->stack_buffer_;
+    }
+    this->heap_buffer_ = std::unique_ptr<uint8_t[]>(new uint8_t[size]);
+    return this->heap_buffer_.get();
+  }
+
+ private:
+  uint8_t stack_buffer_[STACK_SIZE];
+  std::unique_ptr<uint8_t[]> heap_buffer_;
+};
+
 /// @brief Error codes returned by I2CBus and I2CDevice methods
 enum ErrorCode {
   NO_ERROR = 0,                ///< No error found during execution of method
@@ -76,8 +92,8 @@ class I2CBus {
       total_len += read_buffers[i].len;
     }
 
-    SmallBufferWithHeapFallback<128> buffer_alloc(total_len);  // Most I2C reads are small
-    uint8_t *buffer = buffer_alloc.get();
+    SmallBufferWithHeapFallback<128> buffer_alloc;  // Most I2C reads are small
+    uint8_t *buffer = buffer_alloc.get(total_len);
 
     auto err = this->write_readv(address, nullptr, 0, buffer, total_len);
     if (err != ERROR_OK)
@@ -100,8 +116,8 @@ class I2CBus {
       total_len += write_buffers[i].len;
     }
 
-    SmallBufferWithHeapFallback<128> buffer_alloc(total_len);  // Most I2C writes are small
-    uint8_t *buffer = buffer_alloc.get();
+    SmallBufferWithHeapFallback<128> buffer_alloc;  // Most I2C writes are small
+    uint8_t *buffer = buffer_alloc.get(total_len);
 
     size_t pos = 0;
     for (size_t i = 0; i != count; i++) {

esphome/components/lightwaverf/lightwaverf.cpp

@@ -1,4 +1,3 @@
-#include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
 
 #ifdef USE_ESP8266
@@ -45,16 +44,13 @@ void LightWaveRF::send_rx(const std::vector<uint8_t> &msg, uint8_t repeats, bool
 }
 
 void LightWaveRF::print_msg_(uint8_t *msg, uint8_t len) {
-#if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_DEBUG
-  char buffer[65];  // max 10 entries * 6 chars + null
+  char buffer[65];
   ESP_LOGD(TAG, " Received code (len:%i): ", len);
 
-  size_t pos = 0;
   for (int i = 0; i < len; i++) {
-    pos = buf_append_printf(buffer, sizeof(buffer), pos, "0x%02x, ", msg[i]);
+    sprintf(&buffer[i * 6], "0x%02x, ", msg[i]);
   }
   ESP_LOGD(TAG, "[%s]", buffer);
-#endif
 }
 
 void LightWaveRF::dump_config() {

esphome/components/max6956/max6956.cpp

@@ -162,7 +162,7 @@ void MAX6956GPIOPin::pin_mode(gpio::Flags flags) { this->parent_->pin_mode(this-
 bool MAX6956GPIOPin::digital_read() { return this->parent_->digital_read(this->pin_) != this->inverted_; }
 void MAX6956GPIOPin::digital_write(bool value) { this->parent_->digital_write(this->pin_, value != this->inverted_); }
 size_t MAX6956GPIOPin::dump_summary(char *buffer, size_t len) const {
-  return buf_append_printf(buffer, len, 0, "%u via Max6956", this->pin_);
+  return snprintf(buffer, len, "%u via Max6956", this->pin_);
 }
 
 }  // namespace max6956

esphome/components/mcp23016/mcp23016.cpp

@@ -100,7 +100,7 @@ void MCP23016GPIOPin::pin_mode(gpio::Flags flags) { this->parent_->pin_mode(this
 bool MCP23016GPIOPin::digital_read() { return this->parent_->digital_read(this->pin_) != this->inverted_; }
 void MCP23016GPIOPin::digital_write(bool value) { this->parent_->digital_write(this->pin_, value != this->inverted_); }
 size_t MCP23016GPIOPin::dump_summary(char *buffer, size_t len) const {
-  return buf_append_printf(buffer, len, 0, "%u via MCP23016", this->pin_);
+  return snprintf(buffer, len, "%u via MCP23016", this->pin_);
 }
 
 }  // namespace mcp23016

esphome/components/mcp23xxx_base/mcp23xxx_base.cpp

@@ -17,7 +17,7 @@ template<uint8_t N> void MCP23XXXGPIOPin<N>::digital_write(bool value) {
   this->parent_->digital_write(this->pin_, value != this->inverted_);
 }
 template<uint8_t N> size_t MCP23XXXGPIOPin<N>::dump_summary(char *buffer, size_t len) const {
-  return buf_append_printf(buffer, len, 0, "%u via MCP23XXX", this->pin_);
+  return snprintf(buffer, len, "%u via MCP23XXX", this->pin_);
 }
 
 template class MCP23XXXGPIOPin<8>;

esphome/components/mipi_spi/mipi_spi.h

@@ -224,9 +224,12 @@ class MipiSpi : public display::Display,
                     this->madctl_ & MADCTL_BGR ? "BGR" : "RGB", DISPLAYPIXEL * 8, IS_BIG_ENDIAN ? "Big" : "Little");
     if (this->brightness_.has_value())
       esph_log_config(TAG, "  Brightness: %u", this->brightness_.value());
-    log_pin(TAG, "  CS Pin: ", this->cs_);
-    log_pin(TAG, "  Reset Pin: ", this->reset_pin_);
-    log_pin(TAG, "  DC Pin: ", this->dc_pin_);
+    if (this->cs_ != nullptr)
+      esph_log_config(TAG, "  CS Pin: %s", this->cs_->dump_summary().c_str());
+    if (this->reset_pin_ != nullptr)
+      esph_log_config(TAG, "  Reset Pin: %s", this->reset_pin_->dump_summary().c_str());
+    if (this->dc_pin_ != nullptr)
+      esph_log_config(TAG, "  DC Pin: %s", this->dc_pin_->dump_summary().c_str());
     esph_log_config(TAG,
                     "  SPI Mode: %d\n"
                     "  SPI Data rate: %dMHz\n"

esphome/components/mipi_spi/models/adafruit.py

@@ -26,3 +26,5 @@ ST7789V.extend(
     reset_pin=40,
     invert_colors=True,
 )
+
+models = {}

esphome/components/mipi_spi/models/amoled.py

@@ -105,3 +105,6 @@ CO5300 = DriverChip(
         (WCE, 0x00),
     ),
 )
+
+
+models = {}

esphome/components/mipi_spi/models/cyd.py

@@ -1,45 +1,10 @@
-from .ili import ILI9341, ILI9342, ST7789V
+from .ili import ILI9341
 
 ILI9341.extend(
-    # ESP32-2432S028 CYD board with Micro USB, has ILI9341 controller
     "ESP32-2432S028",
     data_rate="40MHz",
-    cs_pin={"number": 15, "ignore_strapping_warning": True},
-    dc_pin={"number": 2, "ignore_strapping_warning": True},
+    cs_pin=15,
+    dc_pin=2,
 )
 
-ST7789V.extend(
-    # ESP32-2432S028 CYD board with USB C + Micro USB, has ST7789V controller
-    "ESP32-2432S028-7789",
-    data_rate="40MHz",
-    cs_pin={"number": 15, "ignore_strapping_warning": True},
-    dc_pin={"number": 2, "ignore_strapping_warning": True},
-)
-
-# fmt: off
-
-ILI9342.extend(
-    # ESP32-2432S028 CYD board with USB C + Micro USB, has ILI9342 controller
-    "ESP32-2432S028-9342",
-    data_rate="40MHz",
-    cs_pin={"number": 15, "ignore_strapping_warning": True},
-    dc_pin={"number": 2, "ignore_strapping_warning": True},
-    initsequence=(
-        (0xCB, 0x39, 0x2C, 0x00, 0x34, 0x02),  # Power Control A
-        (0xCF, 0x00, 0xC1, 0x30),  # Power Control B
-        (0xE8, 0x85, 0x00, 0x78),  # Driver timing control A
-        (0xEA, 0x00, 0x00),  # Driver timing control B
-        (0xED, 0x64, 0x03, 0x12, 0x81),  # Power on sequence control
-        (0xF7, 0x20),  # Pump ratio control
-        (0xC0, 0x23),  # Power Control 1
-        (0xC1, 0x10),  # Power Control 2
-        (0xC5, 0x3E, 0x28),  # VCOM Control 1
-        (0xC7, 0x86),  # VCOM Control 2
-        (0xB1, 0x00, 0x1B),  # Frame Rate Control
-        (0xB6, 0x0A, 0xA2, 0x27, 0x00),  # Display Function Control
-        (0xF2, 0x00),  # Enable 3G
-        (0x26, 0x01),  # Gamma Set
-        (0xE0, 0x00, 0x0C, 0x11, 0x04, 0x11, 0x08, 0x37, 0x89, 0x4C, 0x06, 0x0C, 0x0A, 0x2E, 0x34, 0x0F),  # Positive Gamma Correction
-        (0xE1, 0x00, 0x0B, 0x11, 0x05, 0x13, 0x09, 0x33, 0x67, 0x48, 0x07, 0x0E, 0x0B, 0x23, 0x33, 0x0F),  # Negative Gamma Correction
-    )
-)
+models = {}

esphome/components/mipi_spi/models/ili.py

@@ -148,34 +148,6 @@ ILI9341 = DriverChip(
         ),
     ),
 )
-
-# fmt: off
-
-ILI9342 = DriverChip(
-    "ILI9342",
-    width=320,
-    height=240,
-    mirror_x=True,
-    initsequence=(
-        (0xCB, 0x39, 0x2C, 0x00, 0x34, 0x02),  # Power Control A
-        (0xCF, 0x00, 0xC1, 0x30),  # Power Control B
-        (0xE8, 0x85, 0x00, 0x78),  # Driver timing control A
-        (0xEA, 0x00, 0x00),  # Driver timing control B
-        (0xED, 0x64, 0x03, 0x12, 0x81),  # Power on sequence control
-        (0xF7, 0x20),  # Pump ratio control
-        (0xC0, 0x23),  # Power Control 1
-        (0xC1, 0x10),  # Power Control 2
-        (0xC5, 0x3E, 0x28),  # VCOM Control 1
-        (0xC7, 0x86),  # VCOM Control 2
-        (0xB1, 0x00, 0x1B),  # Frame Rate Control
-        (0xB6, 0x0A, 0xA2, 0x27, 0x00),  # Display Function Control
-        (0xF2, 0x00),  # Enable 3G
-        (0x26, 0x01),  # Gamma Set
-        (0xE0, 0x0F, 0x1F, 0x1C, 0x0C, 0x0F, 0x08, 0x48, 0x98, 0x37, 0x0A, 0x13, 0x04, 0x11, 0x0D, 0x00),  # Positive Gamma
-        (0xE1, 0x0F, 0x32, 0x2E, 0x0B, 0x0D, 0x05, 0x47, 0x75, 0x37, 0x06, 0x10, 0x03, 0x24, 0x20, 0x00),  # Negative Gamma
-    ),
-)
-
 # M5Stack Core2 uses ILI9341 chip - mirror_x disabled for correct orientation
 ILI9341.extend(
     "M5CORE2",
@@ -786,3 +758,5 @@ ST7796.extend(
     dc_pin=0,
     invert_colors=True,
 )
+
+models = {}

esphome/components/mipi_spi/models/jc.py

@@ -588,3 +588,5 @@ DriverChip(
         (0x29, 0x00),
     ),
 )
+
+models = {}

esphome/components/mipi_spi/models/lanbon.py

@@ -11,3 +11,5 @@ ST7789V.extend(
     dc_pin=21,
     reset_pin=18,
 )
+
+models = {}

esphome/components/mipi_spi/models/lilygo.py

@@ -56,3 +56,5 @@ ST7796.extend(
     backlight_pin=48,
     invert_colors=True,
 )
+
+models = {}

esphome/components/mpr121/mpr121.cpp

@@ -154,7 +154,7 @@ void MPR121GPIOPin::digital_write(bool value) {
 }
 
 size_t MPR121GPIOPin::dump_summary(char *buffer, size_t len) const {
-  return buf_append_printf(buffer, len, 0, "ELE%u on MPR121", this->pin_);
+  return snprintf(buffer, len, "ELE%u on MPR121", this->pin_);
 }
 
 }  // namespace mpr121

esphome/components/mqtt/mqtt_client.cpp

@@ -5,7 +5,6 @@
 #include <utility>
 #include "esphome/components/network/util.h"
 #include "esphome/core/application.h"
-#include "esphome/core/entity_base.h"
 #include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
 #include "esphome/core/version.h"
@@ -67,13 +66,10 @@ void MQTTClientComponent::setup() {
         "esphome/discover", [this](const std::string &topic, const std::string &payload) { this->send_device_info_(); },
         2);
 
-    // Format topic on stack - subscribe() copies it
-    // "esphome/ping/" (13) + name (ESPHOME_DEVICE_NAME_MAX_LEN) + null (1)
-    constexpr size_t ping_topic_buffer_size = 13 + ESPHOME_DEVICE_NAME_MAX_LEN + 1;
-    char ping_topic[ping_topic_buffer_size];
-    buf_append_printf(ping_topic, sizeof(ping_topic), 0, "esphome/ping/%s", App.get_name().c_str());
+    std::string topic = "esphome/ping/";
+    topic.append(App.get_name());
     this->subscribe(
-        ping_topic, [this](const std::string &topic, const std::string &payload) { this->send_device_info_(); }, 2);
+        topic, [this](const std::string &topic, const std::string &payload) { this->send_device_info_(); }, 2);
   }
 
   if (this->enable_on_boot_) {
@@ -85,11 +81,8 @@ void MQTTClientComponent::send_device_info_() {
   if (!this->is_connected() or !this->is_discovery_ip_enabled()) {
     return;
   }
-  // Format topic on stack to avoid heap allocation
-  // "esphome/discover/" (17) + name (ESPHOME_DEVICE_NAME_MAX_LEN) + null (1)
-  constexpr size_t topic_buffer_size = 17 + ESPHOME_DEVICE_NAME_MAX_LEN + 1;
-  char topic[topic_buffer_size];
-  buf_append_printf(topic, sizeof(topic), 0, "esphome/discover/%s", App.get_name().c_str());
+  std::string topic = "esphome/discover/";
+  topic.append(App.get_name());
 
   // NOLINTBEGIN(clang-analyzer-cplusplus.NewDeleteLeaks) false positive with ArduinoJson
   this->publish_json(
@@ -507,49 +500,39 @@ bool MQTTClientComponent::publish(const std::string &topic, const std::string &p
 
 bool MQTTClientComponent::publish(const std::string &topic, const char *payload, size_t payload_length, uint8_t qos,
                                   bool retain) {
-  return this->publish(topic.c_str(), payload, payload_length, qos, retain);
+  return publish({.topic = topic, .payload = std::string(payload, payload_length), .qos = qos, .retain = retain});
 }
 
 bool MQTTClientComponent::publish(const MQTTMessage &message) {
-  return this->publish(message.topic.c_str(), message.payload.c_str(), message.payload.length(), message.qos,
-                       message.retain);
-}
-bool MQTTClientComponent::publish_json(const std::string &topic, const json::json_build_t &f, uint8_t qos,
-                                       bool retain) {
-  return this->publish_json(topic.c_str(), f, qos, retain);
-}
-
-bool MQTTClientComponent::publish(const char *topic, const char *payload, size_t payload_length, uint8_t qos,
-                                  bool retain) {
   if (!this->is_connected()) {
+    // critical components will re-transmit their messages
     return false;
   }
-  size_t topic_len = strlen(topic);
-  bool logging_topic = (topic_len == this->log_message_.topic.size()) &&
-                       (memcmp(this->log_message_.topic.c_str(), topic, topic_len) == 0);
-  bool ret = this->mqtt_backend_.publish(topic, payload, payload_length, qos, retain);
+  bool logging_topic = this->log_message_.topic == message.topic;
+  bool ret = this->mqtt_backend_.publish(message);
   delay(0);
   if (!ret && !logging_topic && this->is_connected()) {
     delay(0);
-    ret = this->mqtt_backend_.publish(topic, payload, payload_length, qos, retain);
+    ret = this->mqtt_backend_.publish(message);
     delay(0);
   }
 
   if (!logging_topic) {
     if (ret) {
-      ESP_LOGV(TAG, "Publish(topic='%s' retain=%d qos=%d)", topic, retain, qos);
-      ESP_LOGVV(TAG, "Publish payload (len=%u): '%.*s'", payload_length, static_cast<int>(payload_length), payload);
+      ESP_LOGV(TAG, "Publish(topic='%s' payload='%s' retain=%d qos=%d)", message.topic.c_str(), message.payload.c_str(),
+               message.retain, message.qos);
     } else {
-      ESP_LOGV(TAG, "Publish failed for topic='%s' (len=%u). Will retry", topic, payload_length);
+      ESP_LOGV(TAG, "Publish failed for topic='%s' (len=%u). Will retry", message.topic.c_str(),
+               message.payload.length());
       this->status_momentary_warning("publish", 1000);
     }
   }
   return ret != 0;
 }
-
-bool MQTTClientComponent::publish_json(const char *topic, const json::json_build_t &f, uint8_t qos, bool retain) {
+bool MQTTClientComponent::publish_json(const std::string &topic, const json::json_build_t &f, uint8_t qos,
+                                       bool retain) {
   std::string message = json::build_json(f);
-  return this->publish(topic, message.c_str(), message.length(), qos, retain);
+  return this->publish(topic, message, qos, retain);
 }
 
 void MQTTClientComponent::enable() {
@@ -627,10 +610,18 @@ static bool topic_match(const char *message, const char *subscription) {
 }
 
 void MQTTClientComponent::on_message(const std::string &topic, const std::string &payload) {
-  for (auto &subscription : this->subscriptions_) {
-    if (topic_match(topic.c_str(), subscription.topic.c_str()))
-      subscription.callback(topic, payload);
-  }
+#ifdef USE_ESP8266
+  // on ESP8266, this is called in lwIP/AsyncTCP task; some components do not like running
+  // from a different task.
+  this->defer([this, topic, payload]() {
+#endif
+    for (auto &subscription : this->subscriptions_) {
+      if (topic_match(topic.c_str(), subscription.topic.c_str()))
+        subscription.callback(topic, payload);
+    }
+#ifdef USE_ESP8266
+  });
+#endif
 }
 
 // Setters
@@ -644,8 +635,7 @@ void MQTTClientComponent::set_log_message_template(MQTTMessage &&message) { this
 const MQTTDiscoveryInfo &MQTTClientComponent::get_discovery_info() const { return this->discovery_info_; }
 void MQTTClientComponent::set_topic_prefix(const std::string &topic_prefix, const std::string &check_topic_prefix) {
   if (App.is_name_add_mac_suffix_enabled() && (topic_prefix == check_topic_prefix)) {
-    char buf[ESPHOME_DEVICE_NAME_MAX_LEN + 1];
-    this->topic_prefix_ = str_sanitize_to(buf, App.get_name().c_str());
+    this->topic_prefix_ = str_sanitize(App.get_name());
   } else {
     this->topic_prefix_ = topic_prefix;
   }

esphome/components/mqtt/mqtt_client.h

@@ -229,9 +229,6 @@ class MQTTClientComponent : public Component
   bool publish(const std::string &topic, const char *payload, size_t payload_length, uint8_t qos = 0,
                bool retain = false);
 
-  /// Publish directly without creating MQTTMessage (avoids heap allocation for topic)
-  bool publish(const char *topic, const char *payload, size_t payload_length, uint8_t qos = 0, bool retain = false);
-
   /** Construct and send a JSON MQTT message.
    *
    * @param topic The topic.
@@ -240,9 +237,6 @@ class MQTTClientComponent : public Component
    */
   bool publish_json(const std::string &topic, const json::json_build_t &f, uint8_t qos = 0, bool retain = false);
 
-  /// Publish JSON directly without heap allocation for topic
-  bool publish_json(const char *topic, const json::json_build_t &f, uint8_t qos = 0, bool retain = false);
-
   /// Setup the MQTT client, registering a bunch of callbacks and attempting to connect.
   void setup() override;
   void dump_config() override;

esphome/components/mqtt/mqtt_component.cpp

@@ -48,8 +48,7 @@ void MQTTComponent::set_subscribe_qos(uint8_t qos) { this->subscribe_qos_ = qos;
 void MQTTComponent::set_retain(bool retain) { this->retain_ = retain; }
 
 std::string MQTTComponent::get_discovery_topic_(const MQTTDiscoveryInfo &discovery_info) const {
-  char sanitized_name[ESPHOME_DEVICE_NAME_MAX_LEN + 1];
-  str_sanitize_to(sanitized_name, App.get_name().c_str());
+  std::string sanitized_name = str_sanitize(App.get_name());
   const char *comp_type = this->component_type();
   char object_id_buf[OBJECT_ID_MAX_LEN];
   StringRef object_id = this->get_default_object_id_to_(object_id_buf);
@@ -61,7 +60,7 @@ std::string MQTTComponent::get_discovery_topic_(const MQTTDiscoveryInfo &discove
   p = append_char(p, '/');
   p = append_str(p, comp_type, strlen(comp_type));
   p = append_char(p, '/');
-  p = append_str(p, sanitized_name, strlen(sanitized_name));
+  p = append_str(p, sanitized_name.data(), sanitized_name.size());
   p = append_char(p, '/');
   p = append_str(p, object_id.c_str(), object_id.size());
   p = append_str(p, "/config", 7);

esphome/components/network/ip_address.h

@@ -60,8 +60,6 @@ struct IPAddress {
   }
   IPAddress(const std::string &in_address) { inet_aton(in_address.c_str(), &ip_addr_); }
   IPAddress(const ip_addr_t *other_ip) { ip_addr_ = *other_ip; }
-  // Remove before 2026.8.0
-  ESPDEPRECATED("Use str_to() instead. Removed in 2026.8.0", "2026.2.0")
   std::string str() const {
     char buf[IP_ADDRESS_BUFFER_SIZE];
     this->str_to(buf);
@@ -149,8 +147,6 @@ struct IPAddress {
   bool is_ip4() const { return IP_IS_V4(&ip_addr_); }
   bool is_ip6() const { return IP_IS_V6(&ip_addr_); }
   bool is_multicast() const { return ip_addr_ismulticast(&ip_addr_); }
-  // Remove before 2026.8.0
-  ESPDEPRECATED("Use str_to() instead. Removed in 2026.8.0", "2026.2.0")
   std::string str() const {
     char buf[IP_ADDRESS_BUFFER_SIZE];
     this->str_to(buf);

esphome/components/nextion/nextion.cpp

@@ -1,7 +1,6 @@
 #include "nextion.h"
 #include <cinttypes>
 #include "esphome/core/application.h"
-#include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
 #include "esphome/core/util.h"
 
@@ -1284,9 +1283,8 @@ void Nextion::check_pending_waveform_() {
   size_t buffer_to_send = component->get_wave_buffer_size() < 255 ? component->get_wave_buffer_size()
                                                                   : 255;  // ADDT command can only send 255
 
-  char command[24];  // "addt " + uint8 + "," + uint8 + "," + uint8 + null = max 17 chars
-  buf_append_printf(command, sizeof(command), 0, "addt %u,%u,%zu", component->get_component_id(),
-                    component->get_wave_channel_id(), buffer_to_send);
+  std::string command = "addt " + to_string(component->get_component_id()) + "," +
+                        to_string(component->get_wave_channel_id()) + "," + to_string(buffer_to_send);
   if (!this->send_command_(command)) {
     delete nb;  // NOLINT(cppcoreguidelines-owning-memory)
     this->waveform_queue_.pop_front();

esphome/components/nextion/nextion_upload_arduino.cpp

@@ -34,7 +34,7 @@ int Nextion::upload_by_chunks_(HTTPClient &http_client, uint32_t &range_start) {
   }
 
   char range_header[32];
-  buf_append_printf(range_header, sizeof(range_header), 0, "bytes=%" PRIu32 "-%" PRIu32, range_start, range_end);
+  sprintf(range_header, "bytes=%" PRIu32 "-%" PRIu32, range_start, range_end);
   ESP_LOGV(TAG, "Range: %s", range_header);
   http_client.addHeader("Range", range_header);
   int code = http_client.GET();

esphome/components/nextion/nextion_upload_esp32.cpp

@@ -36,7 +36,7 @@ int Nextion::upload_by_chunks_(esp_http_client_handle_t http_client, uint32_t &r
   }
 
   char range_header[32];
-  buf_append_printf(range_header, sizeof(range_header), 0, "bytes=%" PRIu32 "-%" PRIu32, range_start, range_end);
+  sprintf(range_header, "bytes=%" PRIu32 "-%" PRIu32, range_start, range_end);
   ESP_LOGV(TAG, "Range: %s", range_header);
   esp_http_client_set_header(http_client, "Range", range_header);
   ESP_LOGV(TAG, "Open HTTP");

esphome/components/pca6416a/pca6416a.cpp

@@ -181,7 +181,7 @@ void PCA6416AGPIOPin::pin_mode(gpio::Flags flags) { this->parent_->pin_mode(this
 bool PCA6416AGPIOPin::digital_read() { return this->parent_->digital_read(this->pin_) != this->inverted_; }
 void PCA6416AGPIOPin::digital_write(bool value) { this->parent_->digital_write(this->pin_, value != this->inverted_); }
 size_t PCA6416AGPIOPin::dump_summary(char *buffer, size_t len) const {
-  return buf_append_printf(buffer, len, 0, "%u via PCA6416A", this->pin_);
+  return snprintf(buffer, len, "%u via PCA6416A", this->pin_);
 }
 
 }  // namespace pca6416a

esphome/components/pca9554/pca9554.cpp

@@ -130,7 +130,7 @@ void PCA9554GPIOPin::pin_mode(gpio::Flags flags) { this->parent_->pin_mode(this-
 bool PCA9554GPIOPin::digital_read() { return this->parent_->digital_read(this->pin_) != this->inverted_; }
 void PCA9554GPIOPin::digital_write(bool value) { this->parent_->digital_write(this->pin_, value != this->inverted_); }
 size_t PCA9554GPIOPin::dump_summary(char *buffer, size_t len) const {
-  return buf_append_printf(buffer, len, 0, "%u via PCA9554", this->pin_);
+  return snprintf(buffer, len, "%u via PCA9554", this->pin_);
 }
 
 }  // namespace pca9554

esphome/components/pcf8574/pcf8574.cpp

@@ -107,7 +107,7 @@ void PCF8574GPIOPin::pin_mode(gpio::Flags flags) { this->parent_->pin_mode(this-
 bool PCF8574GPIOPin::digital_read() { return this->parent_->digital_read(this->pin_) != this->inverted_; }
 void PCF8574GPIOPin::digital_write(bool value) { this->parent_->digital_write(this->pin_, value != this->inverted_); }
 size_t PCF8574GPIOPin::dump_summary(char *buffer, size_t len) const {
-  return buf_append_printf(buffer, len, 0, "%u via PCF8574", this->pin_);
+  return snprintf(buffer, len, "%u via PCF8574", this->pin_);
 }
 
 }  // namespace pcf8574

esphome/components/pi4ioe5v6408/pi4ioe5v6408.cpp

@@ -165,7 +165,7 @@ void PI4IOE5V6408GPIOPin::digital_write(bool value) {
   this->parent_->digital_write(this->pin_, value != this->inverted_);
 }
 size_t PI4IOE5V6408GPIOPin::dump_summary(char *buffer, size_t len) const {
-  return buf_append_printf(buffer, len, 0, "%u via PI4IOE5V6408", this->pin_);
+  return snprintf(buffer, len, "%u via PI4IOE5V6408", this->pin_);
 }
 
 }  // namespace pi4ioe5v6408

esphome/components/pipsolar/output/pipsolar_output.cpp

@@ -8,7 +8,7 @@ namespace pipsolar {
 static const char *const TAG = "pipsolar.output";
 
 void PipsolarOutput::write_state(float state) {
-  char tmp[16];
+  char tmp[10];
   snprintf(tmp, sizeof(tmp), this->set_command_, state);
 
   if (std::find(this->possible_values_.begin(), this->possible_values_.end(), state) != this->possible_values_.end()) {

esphome/components/rc522_spi/rc522_spi.cpp

@@ -1,5 +1,4 @@
 #include "rc522_spi.h"
-#include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
 
 // Based on:
@@ -71,7 +70,7 @@ void RC522Spi::pcd_read_register(PcdRegister reg,  ///< The register to read fro
     index++;
 
 #ifdef ESPHOME_LOG_HAS_VERY_VERBOSE
-    buf_append_printf(cstrb, sizeof(cstrb), 0, " %x", values[0]);
+    sprintf(cstrb, " %x", values[0]);
     buf.append(cstrb);
 #endif
   }
@@ -79,7 +78,7 @@ void RC522Spi::pcd_read_register(PcdRegister reg,  ///< The register to read fro
     values[index] = transfer_byte(address);  // Read value and tell that we want to read the same address again.
 
 #ifdef ESPHOME_LOG_HAS_VERY_VERBOSE
-    buf_append_printf(cstrb, sizeof(cstrb), 0, " %x", values[index]);
+    sprintf(cstrb, " %x", values[index]);
     buf.append(cstrb);
 #endif
 
@@ -89,7 +88,7 @@ void RC522Spi::pcd_read_register(PcdRegister reg,  ///< The register to read fro
 
 #ifdef ESPHOME_LOG_HAS_VERY_VERBOSE
   buf = buf + " ";
-  buf_append_printf(cstrb, sizeof(cstrb), 0, "%x", values[index]);
+  sprintf(cstrb, "%x", values[index]);
   buf.append(cstrb);
 
   ESP_LOGVV(TAG, "read_register_array_(%x, %d, , %d) -> %s", reg, count, rx_align, buf.c_str());
@@ -128,7 +127,7 @@ void RC522Spi::pcd_write_register(PcdRegister reg,  ///< The register to write t
     transfer_byte(values[index]);
 
 #ifdef ESPHOME_LOG_HAS_VERY_VERBOSE
-    buf_append_printf(cstrb, sizeof(cstrb), 0, " %x", values[index]);
+    sprintf(cstrb, " %x", values[index]);
     buf.append(cstrb);
 #endif
   }

esphome/components/rf_bridge/rf_bridge.cpp

@@ -1,7 +1,6 @@
 #include "rf_bridge.h"
-#include "esphome/core/application.h"
-#include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
+#include "esphome/core/application.h"
 #include <cinttypes>
 #include <cstring>
 
@@ -73,9 +72,9 @@ bool RFBridgeComponent::parse_bridge_byte_(uint8_t byte) {
 
       data.length = raw[2];
       data.protocol = raw[3];
-      char next_byte[3];  // 2 hex chars + null
+      char next_byte[3];
       for (uint8_t i = 0; i < data.length - 1; i++) {
-        buf_append_printf(next_byte, sizeof(next_byte), 0, "%02X", raw[4 + i]);
+        sprintf(next_byte, "%02X", raw[4 + i]);
         data.code += next_byte;
       }
 
@@ -91,10 +90,10 @@ bool RFBridgeComponent::parse_bridge_byte_(uint8_t byte) {
 
       uint8_t buckets = raw[2] << 1;
       std::string str;
-      char next_byte[3];  // 2 hex chars + null
+      char next_byte[3];
 
       for (uint32_t i = 0; i <= at; i++) {
-        buf_append_printf(next_byte, sizeof(next_byte), 0, "%02X", raw[i]);
+        sprintf(next_byte, "%02X", raw[i]);
         str += next_byte;
         if ((i > 3) && buckets) {
           buckets--;

esphome/components/select/__init__.py

@@ -33,7 +33,7 @@ SelectPtr = Select.operator("ptr")
 # Triggers
 SelectStateTrigger = select_ns.class_(
     "SelectStateTrigger",
-    automation.Trigger.template(cg.StringRef, cg.size_t),
+    automation.Trigger.template(cg.std_string, cg.size_t),
 )
 
 # Actions
@@ -100,7 +100,7 @@ async def setup_select_core_(var, config, *, options: list[str]):
     for conf in config.get(CONF_ON_VALUE, []):
         trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], var)
         await automation.build_automation(
-            trigger, [(cg.StringRef, "x"), (cg.size_t, "i")], conf
+            trigger, [(cg.std_string, "x"), (cg.size_t, "i")], conf
         )
 
     if (mqtt_id := config.get(CONF_MQTT_ID)) is not None:

esphome/components/select/automation.h

@@ -6,11 +6,11 @@
 
 namespace esphome::select {
 
-class SelectStateTrigger : public Trigger<StringRef, size_t> {
+class SelectStateTrigger : public Trigger<std::string, size_t> {
  public:
   explicit SelectStateTrigger(Select *parent) : parent_(parent) {
     parent->add_on_state_callback(
-        [this](size_t index) { this->trigger(StringRef(this->parent_->option_at(index)), index); });
+        [this](size_t index) { this->trigger(std::string(this->parent_->option_at(index)), index); });
   }
 
  protected:

esphome/components/shtcx/shtcx.cpp

@@ -13,14 +13,14 @@ static const uint16_t SHTCX_COMMAND_READ_ID_REGISTER = 0xEFC8;
 static const uint16_t SHTCX_COMMAND_SOFT_RESET = 0x805D;
 static const uint16_t SHTCX_COMMAND_POLLING_H = 0x7866;
 
-static const LogString *shtcx_type_to_string(SHTCXType type) {
+inline const char *to_string(SHTCXType type) {
   switch (type) {
     case SHTCX_TYPE_SHTC3:
-      return LOG_STR("SHTC3");
+      return "SHTC3";
     case SHTCX_TYPE_SHTC1:
-      return LOG_STR("SHTC1");
+      return "SHTC1";
     default:
-      return LOG_STR("UNKNOWN");
+      return "UNKNOWN";
   }
 }
 
@@ -52,7 +52,7 @@ void SHTCXComponent::dump_config() {
   ESP_LOGCONFIG(TAG,
                 "SHTCx:\n"
                 "  Model: %s (%04x)",
-                LOG_STR_ARG(shtcx_type_to_string(this->type_)), this->sensor_id_);
+                to_string(this->type_), this->sensor_id_);
   LOG_I2C_DEVICE(this);
   if (this->is_failed()) {
     ESP_LOGE(TAG, ESP_LOG_MSG_COMM_FAIL);

esphome/components/sim800l/sim800l.cpp

@@ -1,5 +1,4 @@
 #include "sim800l.h"
-#include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
 #include <cstring>
 
@@ -51,8 +50,8 @@ void Sim800LComponent::update() {
   } else if (state_ == STATE_RECEIVED_SMS) {
     // Serial Buffer should have flushed.
     // Send cmd to delete received sms
-    char delete_cmd[20];  // "AT+CMGD=" (8) + uint8_t (max 3) + null = 12 <= 20
-    buf_append_printf(delete_cmd, sizeof(delete_cmd), 0, "AT+CMGD=%d", this->parse_index_);
+    char delete_cmd[20];
+    sprintf(delete_cmd, "AT+CMGD=%d", this->parse_index_);
     this->send_cmd_(delete_cmd);
     this->state_ = STATE_CHECK_SMS;
     this->expect_ack_ = true;

esphome/components/sml/sml_parser.cpp

@@ -104,10 +104,7 @@ std::vector<ObisInfo> SmlFile::get_obis_info() {
 std::string bytes_repr(const BytesView &buffer) {
   std::string repr;
   for (auto const value : buffer) {
-    // max 3: 2 hex digits + null
-    char hex_buf[3];
-    snprintf(hex_buf, sizeof(hex_buf), "%02x", static_cast<unsigned int>(value));
-    repr += hex_buf;
+    repr += str_sprintf("%02x", value & 0xff);
   }
   return repr;
 }
@@ -149,11 +146,7 @@ ObisInfo::ObisInfo(const BytesView &server_id, const SmlNode &val_list_entry) :
 }
 
 std::string ObisInfo::code_repr() const {
-  // max 20: "255-255:255.255.255" (19 chars) + null
-  char buf[20];
-  snprintf(buf, sizeof(buf), "%d-%d:%d.%d.%d", this->code[0], this->code[1], this->code[2], this->code[3],
-           this->code[4]);
-  return buf;
+  return str_sprintf("%d-%d:%d.%d.%d", this->code[0], this->code[1], this->code[2], this->code[3], this->code[4]);
 }
 
 }  // namespace sml

esphome/components/sn74hc165/sn74hc165.cpp

@@ -65,7 +65,7 @@ float SN74HC165Component::get_setup_priority() const { return setup_priority::IO
 bool SN74HC165GPIOPin::digital_read() { return this->parent_->digital_read_(this->pin_) != this->inverted_; }
 
 size_t SN74HC165GPIOPin::dump_summary(char *buffer, size_t len) const {
-  return buf_append_printf(buffer, len, 0, "%u via SN74HC165", this->pin_);
+  return snprintf(buffer, len, "%u via SN74HC165", this->pin_);
 }
 
 }  // namespace sn74hc165

esphome/components/sn74hc595/sn74hc595.cpp

@@ -94,7 +94,7 @@ void SN74HC595GPIOPin::digital_write(bool value) {
   this->parent_->digital_write_(this->pin_, value != this->inverted_);
 }
 size_t SN74HC595GPIOPin::dump_summary(char *buffer, size_t len) const {
-  return buf_append_printf(buffer, len, 0, "%u via SN74HC595", this->pin_);
+  return snprintf(buffer, len, "%u via SN74HC595", this->pin_);
 }
 
 }  // namespace sn74hc595

esphome/components/socket/socket.cpp

@@ -107,9 +107,9 @@ std::unique_ptr<Socket> socket_ip_loop_monitored(int type, int protocol) {
 #endif /* USE_NETWORK_IPV6 */
 }
 
-socklen_t set_sockaddr(struct sockaddr *addr, socklen_t addrlen, const char *ip_address, uint16_t port) {
+socklen_t set_sockaddr(struct sockaddr *addr, socklen_t addrlen, const std::string &ip_address, uint16_t port) {
 #if USE_NETWORK_IPV6
-  if (strchr(ip_address, ':') != nullptr) {
+  if (ip_address.find(':') != std::string::npos) {
     if (addrlen < sizeof(sockaddr_in6)) {
       errno = EINVAL;
       return 0;
@@ -121,14 +121,14 @@ socklen_t set_sockaddr(struct sockaddr *addr, socklen_t addrlen, const char *ip_
 
 #ifdef USE_SOCKET_IMPL_BSD_SOCKETS
     // Use standard inet_pton for BSD sockets
-    if (inet_pton(AF_INET6, ip_address, &server->sin6_addr) != 1) {
+    if (inet_pton(AF_INET6, ip_address.c_str(), &server->sin6_addr) != 1) {
       errno = EINVAL;
       return 0;
     }
 #else
     // Use LWIP-specific functions
     ip6_addr_t ip6;
-    inet6_aton(ip_address, &ip6);
+    inet6_aton(ip_address.c_str(), &ip6);
     memcpy(server->sin6_addr.un.u32_addr, ip6.addr, sizeof(ip6.addr));
 #endif
     return sizeof(sockaddr_in6);
@@ -141,7 +141,7 @@ socklen_t set_sockaddr(struct sockaddr *addr, socklen_t addrlen, const char *ip_
   auto *server = reinterpret_cast<sockaddr_in *>(addr);
   memset(server, 0, sizeof(sockaddr_in));
   server->sin_family = AF_INET;
-  server->sin_addr.s_addr = inet_addr(ip_address);
+  server->sin_addr.s_addr = inet_addr(ip_address.c_str());
   server->sin_port = htons(port);
   return sizeof(sockaddr_in);
 }

esphome/components/socket/socket.h

@@ -87,17 +87,7 @@ std::unique_ptr<Socket> socket_loop_monitored(int domain, int type, int protocol
 std::unique_ptr<Socket> socket_ip_loop_monitored(int type, int protocol);
 
 /// Set a sockaddr to the specified address and port for the IP version used by socket_ip().
-/// @param addr Destination sockaddr structure
-/// @param addrlen Size of the addr buffer
-/// @param ip_address Null-terminated IP address string (IPv4 or IPv6)
-/// @param port Port number in host byte order
-/// @return Size of the sockaddr structure used, or 0 on error
-socklen_t set_sockaddr(struct sockaddr *addr, socklen_t addrlen, const char *ip_address, uint16_t port);
-
-/// Convenience overload for std::string (backward compatible).
-inline socklen_t set_sockaddr(struct sockaddr *addr, socklen_t addrlen, const std::string &ip_address, uint16_t port) {
-  return set_sockaddr(addr, addrlen, ip_address.c_str(), port);
-}
+socklen_t set_sockaddr(struct sockaddr *addr, socklen_t addrlen, const std::string &ip_address, uint16_t port);
 
 /// Set a sockaddr to the any address and specified port for the IP version used by socket_ip().
 socklen_t set_sockaddr_any(struct sockaddr *addr, socklen_t addrlen, uint16_t port);

esphome/components/spi_led_strip/spi_led_strip.cpp

@@ -1,5 +1,4 @@
 #include "spi_led_strip.h"
-#include "esphome/core/helpers.h"
 
 namespace esphome {
 namespace spi_led_strip {
@@ -48,14 +47,15 @@ void SpiLedStrip::dump_config() {
 void SpiLedStrip::write_state(light::LightState *state) {
   if (this->is_failed())
     return;
-#if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERBOSE
-  {
-    char strbuf[49];  // format_hex_pretty_size(16) = 48, fits 16 bytes
-    size_t len = std::min(this->buffer_size_, (size_t) 16);
-    format_hex_pretty_to(strbuf, sizeof(strbuf), this->buf_, len, ' ');
+  if (ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERBOSE) {
+    char strbuf[49];
+    size_t len = std::min(this->buffer_size_, (size_t) (sizeof(strbuf) - 1) / 3);
+    memset(strbuf, 0, sizeof(strbuf));
+    for (size_t i = 0; i != len; i++) {
+      sprintf(strbuf + i * 3, "%02X ", this->buf_[i]);
+    }
     esph_log_v(TAG, "write_state: buf = %s", strbuf);
   }
-#endif
   this->enable();
   this->write_array(this->buf_, this->buffer_size_);
   this->disable();

esphome/components/sprinkler/sprinkler.cpp

@@ -43,11 +43,13 @@ SprinklerControllerSwitch::SprinklerControllerSwitch()
     : turn_on_trigger_(new Trigger<>()), turn_off_trigger_(new Trigger<>()) {}
 
 void SprinklerControllerSwitch::loop() {
-  // Loop is only enabled when f_ has a value (see setup())
+  if (!this->f_.has_value())
+    return;
   auto s = (*this->f_)();
-  if (s.has_value()) {
-    this->publish_state(*s);
-  }
+  if (!s.has_value())
+    return;
+
+  this->publish_state(*s);
 }
 
 void SprinklerControllerSwitch::write_state(bool state) {
@@ -72,13 +74,7 @@ float SprinklerControllerSwitch::get_setup_priority() const { return setup_prior
 Trigger<> *SprinklerControllerSwitch::get_turn_on_trigger() const { return this->turn_on_trigger_; }
 Trigger<> *SprinklerControllerSwitch::get_turn_off_trigger() const { return this->turn_off_trigger_; }
 
-void SprinklerControllerSwitch::setup() {
-  this->state = this->get_initial_state_with_restore_mode().value_or(false);
-  // Disable loop if no state lambda is set - nothing to poll
-  if (!this->f_.has_value()) {
-    this->disable_loop();
-  }
-}
+void SprinklerControllerSwitch::setup() { this->state = this->get_initial_state_with_restore_mode().value_or(false); }
 
 void SprinklerControllerSwitch::dump_config() { LOG_SWITCH("", "Sprinkler Switch", this); }
 
@@ -331,32 +327,25 @@ SprinklerValveOperator *SprinklerValveRunRequest::valve_operator() { return this
 
 SprinklerValveRunRequestOrigin SprinklerValveRunRequest::request_is_from() { return this->origin_; }
 
-Sprinkler::Sprinkler() : Sprinkler("") {}
-Sprinkler::Sprinkler(const char *name) : name_(name) {
-  // The `name` is stored for dump_config logging
+Sprinkler::Sprinkler() {}
+Sprinkler::Sprinkler(const std::string &name) {
+  // The `name` is needed to set timers up, hence non-default constructor
+  // replaces `set_name()` method previously existed
+  this->name_ = name;
   this->timer_.init(2);
-  // Timer names only need to be unique within this component instance
-  this->timer_.push_back({"sm", false, 0, 0, std::bind(&Sprinkler::sm_timer_callback_, this)});
-  this->timer_.push_back({"vs", false, 0, 0, std::bind(&Sprinkler::valve_selection_callback_, this)});
+  this->timer_.push_back({this->name_ + "sm", false, 0, 0, std::bind(&Sprinkler::sm_timer_callback_, this)});
+  this->timer_.push_back({this->name_ + "vs", false, 0, 0, std::bind(&Sprinkler::valve_selection_callback_, this)});
 }
 
-void Sprinkler::setup() {
-  this->all_valves_off_(true);
-  // Start with loop disabled - nothing to do when idle
-  this->disable_loop();
-}
+void Sprinkler::setup() { this->all_valves_off_(true); }
 
 void Sprinkler::loop() {
   for (auto &vo : this->valve_op_) {
     vo.loop();
   }
-  if (this->prev_req_.has_request()) {
-    if (this->prev_req_.has_valve_operator() && this->prev_req_.valve_operator()->state() == IDLE) {
-      this->prev_req_.reset();
-    }
-  } else if (this->state_ == IDLE) {
-    // Nothing more to do - disable loop until next activation
-    this->disable_loop();
+  if (this->prev_req_.has_request() && this->prev_req_.has_valve_operator() &&
+      this->prev_req_.valve_operator()->state() == IDLE) {
+    this->prev_req_.reset();
   }
 }
 
@@ -1344,8 +1333,6 @@ void Sprinkler::start_valve_(SprinklerValveRunRequest *req) {
   if (!this->is_a_valid_valve(req->valve())) {
     return;  // we can't do anything if the valve number isn't valid
   }
-  // Enable loop to monitor valve operator states
-  this->enable_loop();
   for (auto &vo : this->valve_op_) {  // find the first available SprinklerValveOperator, load it and start it up
     if (vo.state() == IDLE) {
       auto run_duration = req->run_duration() ? req->run_duration() : this->valve_run_duration_adjusted(req->valve());
@@ -1588,7 +1575,8 @@ const LogString *Sprinkler::state_as_str_(SprinklerState state) {
 
 void Sprinkler::start_timer_(const SprinklerTimerIndex timer_index) {
   if (this->timer_duration_(timer_index) > 0) {
-    this->set_timeout(this->timer_[timer_index].name, this->timer_duration_(timer_index),
+    // FixedVector ensures timer_ can't be resized, so .c_str() pointers remain valid
+    this->set_timeout(this->timer_[timer_index].name.c_str(), this->timer_duration_(timer_index),
                       this->timer_cbf_(timer_index));
     this->timer_[timer_index].start_time = millis();
     this->timer_[timer_index].active = true;
@@ -1599,7 +1587,7 @@ void Sprinkler::start_timer_(const SprinklerTimerIndex timer_index) {
 
 bool Sprinkler::cancel_timer_(const SprinklerTimerIndex timer_index) {
   this->timer_[timer_index].active = false;
-  return this->cancel_timeout(this->timer_[timer_index].name);
+  return this->cancel_timeout(this->timer_[timer_index].name.c_str());
 }
 
 bool Sprinkler::timer_active_(const SprinklerTimerIndex timer_index) { return this->timer_[timer_index].active; }
@@ -1630,7 +1618,7 @@ void Sprinkler::sm_timer_callback_() {
 }
 
 void Sprinkler::dump_config() {
-  ESP_LOGCONFIG(TAG, "Sprinkler Controller -- %s", this->name_);
+  ESP_LOGCONFIG(TAG, "Sprinkler Controller -- %s", this->name_.c_str());
   if (this->manual_selection_delay_.has_value()) {
     ESP_LOGCONFIG(TAG, "  Manual Selection Delay: %" PRIu32 " seconds", this->manual_selection_delay_.value_or(0));
   }

esphome/components/sprinkler/sprinkler.h

@@ -11,7 +11,7 @@
 
 namespace esphome::sprinkler {
 
-inline constexpr const char *MIN_STR = "min";
+const std::string MIN_STR = "min";
 
 enum SprinklerState : uint8_t {
   // NOTE: these states are used by both SprinklerValveOperator and Sprinkler (the controller)!
@@ -49,7 +49,7 @@ struct SprinklerQueueItem {
 };
 
 struct SprinklerTimer {
-  const char *name;
+  const std::string name;
   bool active;
   uint32_t time;
   uint32_t start_time;
@@ -176,7 +176,7 @@ class SprinklerValveRunRequest {
 class Sprinkler : public Component {
  public:
   Sprinkler();
-  Sprinkler(const char *name);
+  Sprinkler(const std::string &name);
   void setup() override;
   void loop() override;
   void dump_config() override;
@@ -504,7 +504,7 @@ class Sprinkler : public Component {
   uint32_t start_delay_{0};
   uint32_t stop_delay_{0};
 
-  const char *name_{""};
+  std::string name_;
 
   /// Sprinkler controller state
   SprinklerState state_{IDLE};

esphome/components/status/binary_sensor.py

@@ -7,14 +7,14 @@ DEPENDENCIES = ["network"]
 
 status_ns = cg.esphome_ns.namespace("status")
 StatusBinarySensor = status_ns.class_(
-    "StatusBinarySensor", binary_sensor.BinarySensor, cg.PollingComponent
+    "StatusBinarySensor", binary_sensor.BinarySensor, cg.Component
 )
 
 CONFIG_SCHEMA = binary_sensor.binary_sensor_schema(
     StatusBinarySensor,
     device_class=DEVICE_CLASS_CONNECTIVITY,
     entity_category=ENTITY_CATEGORY_DIAGNOSTIC,
-).extend(cv.polling_component_schema("1s"))
+).extend(cv.COMPONENT_SCHEMA)
 
 
 async def to_code(config):

esphome/components/status/status_binary_sensor.cpp

@@ -10,11 +10,12 @@
 #include "esphome/components/api/api_server.h"
 #endif
 
-namespace esphome::status {
+namespace esphome {
+namespace status {
 
 static const char *const TAG = "status";
 
-void StatusBinarySensor::update() {
+void StatusBinarySensor::loop() {
   bool status = network::is_connected();
 #ifdef USE_MQTT
   if (mqtt::global_mqtt_client != nullptr) {
@@ -32,4 +33,5 @@ void StatusBinarySensor::update() {
 void StatusBinarySensor::setup() { this->publish_initial_state(false); }
 void StatusBinarySensor::dump_config() { LOG_BINARY_SENSOR("", "Status Binary Sensor", this); }
 
-}  // namespace esphome::status
+}  // namespace status
+}  // namespace esphome

esphome/components/status/status_binary_sensor.h

@@ -3,11 +3,12 @@
 #include "esphome/core/component.h"
 #include "esphome/components/binary_sensor/binary_sensor.h"
 
-namespace esphome::status {
+namespace esphome {
+namespace status {
 
-class StatusBinarySensor : public binary_sensor::BinarySensor, public PollingComponent {
+class StatusBinarySensor : public binary_sensor::BinarySensor, public Component {
  public:
-  void update() override;
+  void loop() override;
 
   void setup() override;
   void dump_config() override;
@@ -15,4 +16,5 @@ class StatusBinarySensor : public binary_sensor::BinarySensor, public PollingCom
   bool is_status_binary_sensor() const override { return true; }
 };
 
-}  // namespace esphome::status
+}  // namespace status
+}  // namespace esphome

esphome/components/sx1509/sx1509_gpio_pin.cpp

@@ -13,7 +13,7 @@ void SX1509GPIOPin::pin_mode(gpio::Flags flags) { this->parent_->pin_mode(this->
 bool SX1509GPIOPin::digital_read() { return this->parent_->digital_read(this->pin_) != this->inverted_; }
 void SX1509GPIOPin::digital_write(bool value) { this->parent_->digital_write(this->pin_, value != this->inverted_); }
 size_t SX1509GPIOPin::dump_summary(char *buffer, size_t len) const {
-  return buf_append_printf(buffer, len, 0, "%u via sx1509", this->pin_);
+  return snprintf(buffer, len, "%u via sx1509", this->pin_);
 }
 
 }  // namespace sx1509

esphome/components/syslog/esphome_syslog.cpp

@@ -47,27 +47,29 @@ void Syslog::log_(const int level, const char *tag, const char *message, size_t
   size_t remaining = sizeof(packet);
 
   // Write PRI - abort if this fails as packet would be malformed
-  offset = buf_append_printf(packet, sizeof(packet), 0, "<%d>", pri);
-  if (offset == 0) {
-    return;  // PRI always produces at least "<0>" (3 chars), so 0 means error
+  int ret = snprintf(packet, remaining, "<%d>", pri);
+  if (ret <= 0 || static_cast<size_t>(ret) >= remaining) {
+    return;
   }
-  remaining -= offset;
+  offset = ret;
+  remaining -= ret;
 
   // Write timestamp directly into packet (RFC 5424: use "-" if time not valid or strftime fails)
   auto now = this->time_->now();
   size_t ts_written = now.is_valid() ? now.strftime(packet + offset, remaining, "%b %e %H:%M:%S") : 0;
   if (ts_written > 0) {
     offset += ts_written;
+    remaining -= ts_written;
   } else if (remaining > 0) {
     packet[offset++] = '-';
+    remaining--;
   }
 
   // Write hostname, tag, and message
-  offset = buf_append_printf(packet, sizeof(packet), offset, " %s %s: %.*s", App.get_name().c_str(), tag, (int) len,
-                             message);
-  // Clamp to exclude null terminator position if buffer was filled
-  if (offset >= sizeof(packet)) {
-    offset = sizeof(packet) - 1;
+  ret = snprintf(packet + offset, remaining, " %s %s: %.*s", App.get_name().c_str(), tag, (int) len, message);
+  if (ret > 0) {
+    // snprintf returns chars that would be written; clamp to actual buffer space
+    offset += std::min(static_cast<size_t>(ret), remaining > 0 ? remaining - 1 : 0);
   }
 
   if (offset > 0) {

esphome/components/tca9555/tca9555.cpp

@@ -139,7 +139,7 @@ void TCA9555GPIOPin::pin_mode(gpio::Flags flags) { this->parent_->pin_mode(this-
 bool TCA9555GPIOPin::digital_read() { return this->parent_->digital_read(this->pin_) != this->inverted_; }
 void TCA9555GPIOPin::digital_write(bool value) { this->parent_->digital_write(this->pin_, value != this->inverted_); }
 size_t TCA9555GPIOPin::dump_summary(char *buffer, size_t len) const {
-  return buf_append_printf(buffer, len, 0, "%u via TCA9555", this->pin_);
+  return snprintf(buffer, len, "%u via TCA9555", this->pin_);
 }
 
 }  // namespace tca9555

esphome/components/template/select/__init__.py

@@ -88,5 +88,5 @@ async def to_code(config):
 
     if CONF_SET_ACTION in config:
         await automation.build_automation(
-            var.get_set_trigger(), [(cg.StringRef, "x")], config[CONF_SET_ACTION]
+            var.get_set_trigger(), [(cg.std_string, "x")], config[CONF_SET_ACTION]
         )

esphome/components/template/select/template_select.cpp

@@ -41,7 +41,7 @@ void TemplateSelect::update() {
 }
 
 void TemplateSelect::control(size_t index) {
-  this->set_trigger_->trigger(StringRef(this->option_at(index)));
+  this->set_trigger_->trigger(std::string(this->option_at(index)));
 
   if (this->optimistic_)
     this->publish_state(index);

esphome/components/template/select/template_select.h

@@ -4,7 +4,6 @@
 #include "esphome/core/automation.h"
 #include "esphome/core/component.h"
 #include "esphome/core/preferences.h"
-#include "esphome/core/string_ref.h"
 #include "esphome/core/template_lambda.h"
 
 namespace esphome::template_ {
@@ -18,7 +17,7 @@ class TemplateSelect final : public select::Select, public PollingComponent {
   void dump_config() override;
   float get_setup_priority() const override { return setup_priority::HARDWARE; }
 
-  Trigger<StringRef> *get_set_trigger() const { return this->set_trigger_; }
+  Trigger<std::string> *get_set_trigger() const { return this->set_trigger_; }
   void set_optimistic(bool optimistic) { this->optimistic_ = optimistic; }
   void set_initial_option_index(size_t initial_option_index) { this->initial_option_index_ = initial_option_index; }
   void set_restore_value(bool restore_value) { this->restore_value_ = restore_value; }
@@ -28,7 +27,7 @@ class TemplateSelect final : public select::Select, public PollingComponent {
   bool optimistic_ = false;
   size_t initial_option_index_{0};
   bool restore_value_ = false;
-  Trigger<StringRef> *set_trigger_ = new Trigger<StringRef>();
+  Trigger<std::string> *set_trigger_ = new Trigger<std::string>();
   TemplateLambda<std::string> f_;
 
   ESPPreferenceObject pref_;

esphome/components/tormatic/tormatic_protocol.h

@@ -55,7 +55,6 @@ enum MessageType : uint16_t {
   COMMAND = 0x0106,
 };
 
-// Max string length: 7 ("Unknown"/"Command"). Update print() buffer sizes if adding longer strings.
 inline const char *message_type_to_str(MessageType t) {
   switch (t) {
     case STATUS:
@@ -84,11 +83,7 @@ struct MessageHeader {
   }
 
   std::string print() {
-    // 64 bytes: "MessageHeader: seq " + uint16 + ", len " + uint32 + ", type " + type + safety margin
-    char buf[64];
-    buf_append_printf(buf, sizeof(buf), 0, "MessageHeader: seq %d, len %d, type %s", this->seq, this->len,
-                      message_type_to_str(this->type));
-    return buf;
+    return str_sprintf("MessageHeader: seq %d, len %d, type %s", this->seq, this->len, message_type_to_str(this->type));
   }
 
   void byteswap() {
@@ -136,7 +131,6 @@ inline CoverOperation gate_status_to_cover_operation(GateStatus s) {
   return COVER_OPERATION_IDLE;
 }
 
-// Max string length: 11 ("Ventilating"). Update print() buffer sizes if adding longer strings.
 inline const char *gate_status_to_str(GateStatus s) {
   switch (s) {
     case PAUSED:
@@ -176,12 +170,7 @@ struct StatusReply {
   GateStatus state;
   uint8_t trailer = 0x0;
 
-  std::string print() {
-    // 48 bytes: "StatusReply: state " (19) + state (11) + safety margin
-    char buf[48];
-    buf_append_printf(buf, sizeof(buf), 0, "StatusReply: state %s", gate_status_to_str(this->state));
-    return buf;
-  }
+  std::string print() { return str_sprintf("StatusReply: state %s", gate_status_to_str(this->state)); }
 
   void byteswap(){};
 } __attribute__((packed));
@@ -213,12 +202,7 @@ struct CommandRequestReply {
   CommandRequestReply() = default;
   CommandRequestReply(GateStatus state) { this->state = state; }
 
-  std::string print() {
-    // 56 bytes: "CommandRequestReply: state " (27) + state (11) + safety margin
-    char buf[56];
-    buf_append_printf(buf, sizeof(buf), 0, "CommandRequestReply: state %s", gate_status_to_str(this->state));
-    return buf;
-  }
+  std::string print() { return str_sprintf("CommandRequestReply: state %s", gate_status_to_str(this->state)); }
 
   void byteswap() { this->type = convert_big_endian(this->type); }
 } __attribute__((packed));

esphome/components/toshiba/toshiba.cpp

@@ -1,6 +1,5 @@
 #include "toshiba.h"
 #include "esphome/components/remote_base/toshiba_ac_protocol.h"
-#include "esphome/core/helpers.h"
 
 #include <vector>
 
@@ -428,17 +427,10 @@ void ToshibaClimate::setup() {
   // Never send nan to HA
   if (std::isnan(this->target_temperature))
     this->target_temperature = 24;
-#if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERBOSE
   // Log final state for debugging HA errors
-  const char *fan_mode_str = "NONE";
-  char fan_mode_buf[4];  // max 3 digits for fan mode enum + null
-  if (this->fan_mode.has_value()) {
-    buf_append_printf(fan_mode_buf, sizeof(fan_mode_buf), 0, "%d", static_cast<int>(this->fan_mode.value()));
-    fan_mode_str = fan_mode_buf;
-  }
-  ESP_LOGV(TAG, "Setup complete - Mode: %d, Fan: %s, Swing: %d, Temp: %.1f", static_cast<int>(this->mode), fan_mode_str,
+  ESP_LOGV(TAG, "Setup complete - Mode: %d, Fan: %s, Swing: %d, Temp: %.1f", static_cast<int>(this->mode),
+           this->fan_mode.has_value() ? std::to_string(static_cast<int>(this->fan_mode.value())).c_str() : "NONE",
            static_cast<int>(this->swing_mode), this->target_temperature);
-#endif
 }
 
 void ToshibaClimate::transmit_state() {

esphome/components/tuya/light/tuya_light.cpp

@@ -191,7 +191,7 @@ void TuyaLight::write_state(light::LightState *state) {
       case TuyaColorType::RGB: {
         char buffer[7];
         const char *format_str = this->color_type_lowercase_ ? "%02x%02x%02x" : "%02X%02X%02X";
-        snprintf(buffer, sizeof(buffer), format_str, int(red * 255), int(green * 255), int(blue * 255));
+        sprintf(buffer, format_str, int(red * 255), int(green * 255), int(blue * 255));
         color_value = buffer;
         break;
       }
@@ -201,7 +201,7 @@ void TuyaLight::write_state(light::LightState *state) {
         rgb_to_hsv(red, green, blue, hue, saturation, value);
         char buffer[13];
         const char *format_str = this->color_type_lowercase_ ? "%04x%04x%04x" : "%04X%04X%04X";
-        snprintf(buffer, sizeof(buffer), format_str, hue, int(saturation * 1000), int(value * 1000));
+        sprintf(buffer, format_str, hue, int(saturation * 1000), int(value * 1000));
         color_value = buffer;
         break;
       }
@@ -211,8 +211,8 @@ void TuyaLight::write_state(light::LightState *state) {
         rgb_to_hsv(red, green, blue, hue, saturation, value);
         char buffer[15];
         const char *format_str = this->color_type_lowercase_ ? "%02x%02x%02x%04x%02x%02x" : "%02X%02X%02X%04X%02X%02X";
-        snprintf(buffer, sizeof(buffer), format_str, int(red * 255), int(green * 255), int(blue * 255), hue,
-                 int(saturation * 255), int(value * 255));
+        sprintf(buffer, format_str, int(red * 255), int(green * 255), int(blue * 255), hue, int(saturation * 255),
+                int(value * 255));
         color_value = buffer;
         break;
       }

esphome/components/tuya/text_sensor/tuya_text_sensor.cpp

@@ -24,7 +24,7 @@ void TuyaTextSensor::setup() {
       }
       case TuyaDatapointType::ENUM: {
         char buf[4];  // uint8_t max is 3 digits + null
-        buf_append_printf(buf, sizeof(buf), 0, "%u", datapoint.value_enum);
+        snprintf(buf, sizeof(buf), "%u", datapoint.value_enum);
         ESP_LOGD(TAG, "MCU reported text sensor %u is: %s", datapoint.id, buf);
         this->publish_state(buf);
         break;

esphome/components/uart/uart_debugger.cpp

@@ -107,7 +107,7 @@ void UARTDebug::log_hex(UARTDirection direction, std::vector<uint8_t> bytes, uin
     if (i > 0) {
       res += separator;
     }
-    buf_append_printf(buf, sizeof(buf), 0, "%02X", bytes[i]);
+    sprintf(buf, "%02X", bytes[i]);
     res += buf;
   }
   ESP_LOGD(TAG, "%s", res.c_str());
@@ -147,7 +147,7 @@ void UARTDebug::log_string(UARTDirection direction, std::vector<uint8_t> bytes)
     } else if (bytes[i] == 92) {
       res += "\\\\";
     } else if (bytes[i] < 32 || bytes[i] > 127) {
-      buf_append_printf(buf, sizeof(buf), 0, "\\x%02X", bytes[i]);
+      sprintf(buf, "\\x%02X", bytes[i]);
       res += buf;
     } else {
       res += bytes[i];
@@ -166,13 +166,11 @@ void UARTDebug::log_int(UARTDirection direction, std::vector<uint8_t> bytes, uin
   } else {
     res += ">>> ";
   }
-  char buf[4];  // max 3 digits for uint8_t (255) + null
   for (size_t i = 0; i < len; i++) {
     if (i > 0) {
       res += separator;
     }
-    buf_append_printf(buf, sizeof(buf), 0, "%u", bytes[i]);
-    res += buf;
+    res += to_string(bytes[i]);
   }
   ESP_LOGD(TAG, "%s", res.c_str());
   delay(10);
@@ -191,7 +189,7 @@ void UARTDebug::log_binary(UARTDirection direction, std::vector<uint8_t> bytes,
     if (i > 0) {
       res += separator;
     }
-    buf_append_printf(buf, sizeof(buf), 0, "0b" BYTE_TO_BINARY_PATTERN " (0x%02X)", BYTE_TO_BINARY(bytes[i]), bytes[i]);
+    sprintf(buf, "0b" BYTE_TO_BINARY_PATTERN " (0x%02X)", BYTE_TO_BINARY(bytes[i]), bytes[i]);
     res += buf;
   }
   ESP_LOGD(TAG, "%s", res.c_str());

esphome/components/uptime/text_sensor/uptime_text_sensor.cpp

@@ -9,12 +9,17 @@ namespace uptime {
 
 static const char *const TAG = "uptime.sensor";
 
+// Clamp position to valid buffer range when snprintf indicates truncation
+static size_t clamp_buffer_pos(size_t pos, size_t buf_size) { return pos < buf_size ? pos : buf_size - 1; }
+
 static void append_unit(char *buf, size_t buf_size, size_t &pos, const char *separator, unsigned value,
                         const char *label) {
   if (pos > 0) {
-    pos = buf_append_printf(buf, buf_size, pos, "%s", separator);
+    pos += snprintf(buf + pos, buf_size - pos, "%s", separator);
+    pos = clamp_buffer_pos(pos, buf_size);
   }
-  pos = buf_append_printf(buf, buf_size, pos, "%u%s", value, label);
+  pos += snprintf(buf + pos, buf_size - pos, "%u%s", value, label);
+  pos = clamp_buffer_pos(pos, buf_size);
 }
 
 void UptimeTextSensor::setup() {

esphome/components/voice_assistant/voice_assistant.h

@@ -81,8 +81,6 @@ struct Timer {
              this->id.c_str(), this->name.c_str(), this->total_seconds, this->seconds_left, YESNO(this->is_active));
     return buffer.data();
   }
-  // Remove before 2026.8.0
-  ESPDEPRECATED("Use to_str() instead. Removed in 2026.8.0", "2026.2.0")
   std::string to_string() const {
     char buffer[TO_STR_BUFFER_SIZE];
     return this->to_str(buffer);

esphome/components/web_server/web_server.cpp

@@ -1188,7 +1188,11 @@ std::string WebServer::date_json_(datetime::DateEntity *obj, JsonDetail start_co
 
   // Format: YYYY-MM-DD (max 10 chars + null)
   char value[12];
-  buf_append_printf(value, sizeof(value), 0, "%d-%02d-%02d", obj->year, obj->month, obj->day);
+#ifdef USE_ESP8266
+  snprintf_P(value, sizeof(value), PSTR("%d-%02d-%02d"), obj->year, obj->month, obj->day);
+#else
+  snprintf(value, sizeof(value), "%d-%02d-%02d", obj->year, obj->month, obj->day);
+#endif
   set_json_icon_state_value(root, obj, "date", value, value, start_config);
   if (start_config == DETAIL_ALL) {
     this->add_sorting_info_(root, obj);
@@ -1247,7 +1251,11 @@ std::string WebServer::time_json_(datetime::TimeEntity *obj, JsonDetail start_co
 
   // Format: HH:MM:SS (8 chars + null)
   char value[12];
-  buf_append_printf(value, sizeof(value), 0, "%02d:%02d:%02d", obj->hour, obj->minute, obj->second);
+#ifdef USE_ESP8266
+  snprintf_P(value, sizeof(value), PSTR("%02d:%02d:%02d"), obj->hour, obj->minute, obj->second);
+#else
+  snprintf(value, sizeof(value), "%02d:%02d:%02d", obj->hour, obj->minute, obj->second);
+#endif
   set_json_icon_state_value(root, obj, "time", value, value, start_config);
   if (start_config == DETAIL_ALL) {
     this->add_sorting_info_(root, obj);
@@ -1306,8 +1314,13 @@ std::string WebServer::datetime_json_(datetime::DateTimeEntity *obj, JsonDetail
 
   // Format: YYYY-MM-DD HH:MM:SS (max 19 chars + null)
   char value[24];
-  buf_append_printf(value, sizeof(value), 0, "%d-%02d-%02d %02d:%02d:%02d", obj->year, obj->month, obj->day, obj->hour,
-                    obj->minute, obj->second);
+#ifdef USE_ESP8266
+  snprintf_P(value, sizeof(value), PSTR("%d-%02d-%02d %02d:%02d:%02d"), obj->year, obj->month, obj->day, obj->hour,
+             obj->minute, obj->second);
+#else
+  snprintf(value, sizeof(value), "%d-%02d-%02d %02d:%02d:%02d", obj->year, obj->month, obj->day, obj->hour, obj->minute,
+           obj->second);
+#endif
   set_json_icon_state_value(root, obj, "datetime", value, value, start_config);
   if (start_config == DETAIL_ALL) {
     this->add_sorting_info_(root, obj);

esphome/components/weikai/weikai.cpp

@@ -246,7 +246,7 @@ void WeikaiGPIOPin::setup() {
 }
 
 size_t WeikaiGPIOPin::dump_summary(char *buffer, size_t len) const {
-  return buf_append_printf(buffer, len, 0, "%u via WeiKai %s", this->pin_, this->parent_->get_name());
+  return snprintf(buffer, len, "%u via WeiKai %s", this->pin_, this->parent_->get_name());
 }
 
 ///////////////////////////////////////////////////////////////////////////////

esphome/components/wiegand/wiegand.cpp

@@ -1,5 +1,4 @@
 #include "wiegand.h"
-#include <cinttypes>
 #include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
 
@@ -70,35 +69,32 @@ void Wiegand::loop() {
   for (auto *trigger : this->raw_triggers_)
     trigger->trigger(count, value);
   if (count == 26) {
-    char tag_buf[12];  // max 8 digits for 24-bit value + null
-    buf_append_printf(tag_buf, sizeof(tag_buf), 0, "%" PRIu32, static_cast<uint32_t>((value >> 1) & 0xffffff));
-    ESP_LOGD(TAG, "received 26-bit tag: %s", tag_buf);
+    std::string tag = to_string((value >> 1) & 0xffffff);
+    ESP_LOGD(TAG, "received 26-bit tag: %s", tag.c_str());
     if (!check_eparity(value, 13, 13) || !check_oparity(value, 0, 13)) {
       ESP_LOGW(TAG, "invalid parity");
       return;
     }
     for (auto *trigger : this->tag_triggers_)
-      trigger->trigger(tag_buf);
+      trigger->trigger(tag);
   } else if (count == 34) {
-    char tag_buf[12];  // max 10 digits for 32-bit value + null
-    buf_append_printf(tag_buf, sizeof(tag_buf), 0, "%" PRIu32, static_cast<uint32_t>((value >> 1) & 0xffffffff));
-    ESP_LOGD(TAG, "received 34-bit tag: %s", tag_buf);
+    std::string tag = to_string((value >> 1) & 0xffffffff);
+    ESP_LOGD(TAG, "received 34-bit tag: %s", tag.c_str());
     if (!check_eparity(value, 17, 17) || !check_oparity(value, 0, 17)) {
       ESP_LOGW(TAG, "invalid parity");
       return;
     }
     for (auto *trigger : this->tag_triggers_)
-      trigger->trigger(tag_buf);
+      trigger->trigger(tag);
   } else if (count == 37) {
-    char tag_buf[12];  // max 11 digits for 35-bit value + null
-    buf_append_printf(tag_buf, sizeof(tag_buf), 0, "%" PRIu64, static_cast<uint64_t>((value >> 1) & 0x7ffffffff));
-    ESP_LOGD(TAG, "received 37-bit tag: %s", tag_buf);
+    std::string tag = to_string((value >> 1) & 0x7ffffffff);
+    ESP_LOGD(TAG, "received 37-bit tag: %s", tag.c_str());
     if (!check_eparity(value, 18, 19) || !check_oparity(value, 0, 19)) {
       ESP_LOGW(TAG, "invalid parity");
       return;
     }
     for (auto *trigger : this->tag_triggers_)
-      trigger->trigger(tag_buf);
+      trigger->trigger(tag);
   } else if (count == 4) {
     for (auto *trigger : this->key_triggers_)
       trigger->trigger(value);

esphome/components/wifi/wifi_component_libretiny.cpp

@@ -660,21 +660,27 @@ void WiFiComponent::wifi_scan_done_callback_() {
   this->scan_result_.clear();
   this->scan_done_ = true;
 
-  int16_t num = WiFi.scanComplete();
-  if (num < 0)
+  // Access scan data directly to avoid String allocation from WiFi.SSID(i)
+  // WiFi.scan is public in LibreTiny (WiFi.h)
+  if (WiFi.scan == nullptr || WiFi.scan->running)
     return;
 
-  this->scan_result_.init(static_cast<unsigned int>(num));
-  for (int i = 0; i < num; i++) {
-    String ssid = WiFi.SSID(i);
-    wifi_auth_mode_t authmode = WiFi.encryptionType(i);
-    int32_t rssi = WiFi.RSSI(i);
-    uint8_t *bssid = WiFi.BSSID(i);
-    int32_t channel = WiFi.channel(i);
+  uint8_t num = WiFi.scan->count;
+  if (num == 0) {
+    WiFi.scanDelete();
+    return;
+  }
 
-    this->scan_result_.emplace_back(bssid_t{bssid[0], bssid[1], bssid[2], bssid[3], bssid[4], bssid[5]},
-                                    std::string(ssid.c_str()), channel, rssi, authmode != WIFI_AUTH_OPEN,
-                                    ssid.length() == 0);
+  this->scan_result_.init(num);
+  for (uint8_t i = 0; i < num; i++) {
+    const auto &ap = WiFi.scan->ap[i];
+    const char *ssid_cstr = ap.ssid;
+    size_t ssid_len = ssid_cstr ? strlen(ssid_cstr) : 0;
+
+    this->scan_result_.emplace_back(bssid_t{ap.bssid.addr[0], ap.bssid.addr[1], ap.bssid.addr[2], ap.bssid.addr[3],
+                                            ap.bssid.addr[4], ap.bssid.addr[5]},
+                                    std::string(ssid_cstr ? ssid_cstr : "", ssid_len), ap.channel, ap.rssi,
+                                    ap.auth != WIFI_AUTH_OPEN, ssid_len == 0);
   }
   WiFi.scanDelete();
 #ifdef USE_WIFI_SCAN_RESULTS_LISTENERS

esphome/components/wl_134/wl_134.cpp

@@ -1,5 +1,4 @@
 #include "wl_134.h"
-#include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
 
 #include <cinttypes>
@@ -79,8 +78,8 @@ Wl134Component::Rfid134Error Wl134Component::read_packet_() {
            reading.id, reading.country, reading.isData ? "true" : "false", reading.isAnimal ? "true" : "false",
            reading.reserved0, reading.reserved1);
 
-  char buf[20];  // "%03d" (3) + "%012" PRId64 (12) + null = 16 max
-  buf_append_printf(buf, sizeof(buf), 0, "%03d%012" PRId64, reading.country, reading.id);
+  char buf[20];
+  sprintf(buf, "%03d%012lld", reading.country, reading.id);
   this->publish_state(buf);
   if (this->do_reset_) {
     this->set_timeout(1000, [this]() { this->publish_state(""); });

esphome/components/xl9535/xl9535.cpp

@@ -111,7 +111,7 @@ void XL9535Component::pin_mode(uint8_t pin, gpio::Flags mode) {
 void XL9535GPIOPin::setup() { this->pin_mode(this->flags_); }
 
 size_t XL9535GPIOPin::dump_summary(char *buffer, size_t len) const {
-  return buf_append_printf(buffer, len, 0, "%u via XL9535", this->pin_);
+  return snprintf(buffer, len, "%u via XL9535", this->pin_);
 }
 
 void XL9535GPIOPin::pin_mode(gpio::Flags flags) { this->parent_->pin_mode(this->pin_, flags); }

esphome/components/zephyr/preferences.cpp

@@ -5,8 +5,6 @@
 #include "esphome/core/preferences.h"
 #include "esphome/core/log.h"
 #include <zephyr/settings/settings.h>
-#include <cinttypes>
-#include <cstring>
 
 namespace esphome {
 namespace zephyr {
@@ -15,9 +13,6 @@ static const char *const TAG = "zephyr.preferences";
 
 #define ESPHOME_SETTINGS_KEY "esphome"
 
-// Buffer size for key: "esphome/" (8) + max hex uint32 (8) + null terminator (1) = 17; use 20 for safety margin
-static constexpr size_t KEY_BUFFER_SIZE = 20;
-
 class ZephyrPreferenceBackend : public ESPPreferenceBackend {
  public:
   ZephyrPreferenceBackend(uint32_t type) { this->type_ = type; }
@@ -32,9 +27,7 @@ class ZephyrPreferenceBackend : public ESPPreferenceBackend {
 
   bool load(uint8_t *data, size_t len) override {
     if (len != this->data.size()) {
-      char key_buf[KEY_BUFFER_SIZE];
-      this->format_key(key_buf, sizeof(key_buf));
-      ESP_LOGE(TAG, "size of setting key %s changed, from: %u, to: %u", key_buf, this->data.size(), len);
+      ESP_LOGE(TAG, "size of setting key %s changed, from: %u, to: %u", get_key().c_str(), this->data.size(), len);
       return false;
     }
     std::memcpy(data, this->data.data(), len);
@@ -43,7 +36,7 @@ class ZephyrPreferenceBackend : public ESPPreferenceBackend {
   }
 
   uint32_t get_type() const { return this->type_; }
-  void format_key(char *buf, size_t size) const { snprintf(buf, size, ESPHOME_SETTINGS_KEY "/%" PRIx32, this->type_); }
+  std::string get_key() const { return str_sprintf(ESPHOME_SETTINGS_KEY "/%" PRIx32, this->type_); }
 
   std::vector<uint8_t> data;
 
@@ -92,9 +85,7 @@ class ZephyrPreferences : public ESPPreferences {
     }
     printf("type %u size %u\n", type, this->backends_.size());
     auto *pref = new ZephyrPreferenceBackend(type);  // NOLINT(cppcoreguidelines-owning-memory)
-    char key_buf[KEY_BUFFER_SIZE];
-    pref->format_key(key_buf, sizeof(key_buf));
-    ESP_LOGD(TAG, "Add new setting %s.", key_buf);
+    ESP_LOGD(TAG, "Add new setting %s.", pref->get_key().c_str());
     this->backends_.push_back(pref);
     return ESPPreferenceObject(pref);
   }
@@ -143,10 +134,9 @@ class ZephyrPreferences : public ESPPreferences {
 
   static int export_settings(int (*cb)(const char *name, const void *value, size_t val_len)) {
     for (auto *backend : static_cast<ZephyrPreferences *>(global_preferences)->backends_) {
-      char name[KEY_BUFFER_SIZE];
-      backend->format_key(name, sizeof(name));
-      int err = cb(name, backend->data.data(), backend->data.size());
-      ESP_LOGD(TAG, "save in flash, name %s, len %u, err %d", name, backend->data.size(), err);
+      auto name = backend->get_key();
+      int err = cb(name.c_str(), backend->data.data(), backend->data.size());
+      ESP_LOGD(TAG, "save in flash, name %s, len %u, err %d", name.c_str(), backend->data.size(), err);
     }
     return 0;
   }